Mini Base Design: The Dwarf

A few months ago, I was introduced to a somewhat-local geek club — somewhat local in the sense that it’s not really local, but it’s not too far out from my usual daily commute. Every couple of months or so, they organize a fantasy-themed event, which my D&D party got a whiff of. During those events, they mildly promote their main activity — painting minis for D&D and warhammer and shit — and before I knew it, I was spending my Thursdays over there with a scary regularity.

While the first event had no mini painting contest, things soon got spicy. Events now also feature a mini painting contest. Mini contest has some limitations:

• must fit with the event theme
• Base up to 50mm
• Overhangs are allowed

The theme is known well in advance and if you lack a mini to paint, the local 3D print gurus are more than happy to let you pick one from their latest print batch. They will even print you any mini you want, as long as you provide a stl file (or pick one from their catalogue).

The current event is winter-themed, which I like. Another thing I also like is setting goals way to high. I want to have a base that includes a light source to put on my shelf, and this contest seems sufficient motivation for me to design something up.

Something along these lines:

Housing for the Electronics

Being not a very large fan of FreeCAD, I decided I’m going to try Blender with CADSketcher. This lasted for about 5 minutes, until I discovered that trying to do anything at all crashes Blender on my machine. With that approach being all Twix and no bueno⁰¹Yes I know “no bueno” is not grammatically correct, but chances of a spanish-speaking audiences stumbling over a blog that’s not even read by English speakers is small enough I’m willing to go for the pun, I guess FreeCAD gets another go.

And after googling how to hotkey shit, the experience suddenly became much less miserable¹²though not as un-miserable as it would be, had I learned how to use CAD properly.

Things that we’re gonna need

Before we start designing, we need to figure out what exactly do we need to fit into the base in order to determine our “space budget”. Unceremoniously:

• USB port, preferably type C, for power while sitting on my shelf at home
• RGB LEDs that go into the runestone
• arduino / esprutino, for driving LEDs
• 5V (or so) battery

Creating the models

USB is easy. You can get female type C plugs on a small PCB for cheap from Amazon. Those run at around 15x10x4 mm. Esprutino will cost us 28mm x 22.5mm x 4mm (+ any headers, if we decide to use headers instead of just soldering wires directly to it). LED strip is 12mm wide and 3mm tall, with LED spacing of 7mm (center-to-center).

Easy.

After an afternoon of work of searching for USB plug dimensions and then designing the model, we have our first version of the base.

What’s considerably less easy are the batteries. Initially, I intended on using a small lithium bag battery (with a charging/discharging circuit that gives me 5V). But there’s a problem: finding niche products in a small country is hard, so I’ll have to look elsewhere.

German Amazon won’t deliver batteries to Slovenia. It says that it does on the listing, but when you go to click the “buy” button you suddenly get “oopsie, cannot deliver to your address.”

The next two options are three AAA batteries, giving you 4.5V. Friend who dabbles with hardware a bit more tells me that 4.5V is enough to run 5V microcontroller and LEDs, but I’m concerned that if the voltage starts at 4.5V, it’s probably going to drop below minimum voltage faster than I’d like. Alternatively, I could buy four rechargeable AAA batteries, which would give me 4.8 V when in series. This looks much better, until you look at the price: €10-20 for capacities that are pretty low, all things considered.

But you know what else is €10-20€?

That’s right, a cheap, single-cell power bank. Unlike the rechargeable AAA batteries, a standard USB power bank can be effortlessly reused in other projects — or even as a portable power source to power my painting lamp. This reusability puts the power bank high on my “let’s try to avoid buying too many one-off items.” However, it comes with the considerable space cost: 95mm x 26mm x 22mm (ish) for the power bank — but that does not account for the size of the USB plug, which would push the necessary enclosure size way over 100mm.

But we can get creative. Inside the power bank is a 65mm (ish) cell with a 20mm (ish) diameter, and the charging/discharging circuit (20x20x20-ish mm). Still bigger than I like, but we can disassemble the power bank—

DISCLAIMER: this is dangerous as hell. Do not do this. It voids your warranty and if you accidentally short-circuit the terminals of the battery, that can result in a fire that produces a bunch of highly toxic fumes. If you ever do this, I am not responsible for whatever happens. Use your brain, even if I don’t.

— and re-arrange the placement of the battery and the charging circuit by stacking the USB ports on top of the cell. My design for the battery case (that’s going to get inserted into the base) is ~73mm wide, with another 12mm for screw holes needed to keep the battery case shut.

It is also 39mm tall. Which is a problem, because now our entire base is going to be 50mm tall before we start to model our terrain. It also limits the minimum height of the ledge the dwarf will stand on, which is… less than ideal.

We’d probably be better off if we changed the location of the lids and the screws to the top.

But there’s another problem. If I wanted to narrow the ledge under the dwarf to something not literally half his size, with the ledge overhang poking out at an angle I want, I’d have to extend the ledge much further than desired 20mm out from the base.

This also ignores the question of how I’m gonna get the battery through the hole on the bottom.

Perhaps it’s time to look at the problem and ask ourselves a question that should have been much earlier in the process:

Can we cut out anything that we don’t need?

Turns out yes, we could. We don’t need the type C port and battery simultaneously, meaning our type C port can be removable. At the first sight, that allows us to try and sculpt the base to support diagonal insertion of the battery. But the measuring tool says that at the shallowest feasible angle for insertion, the tip of the overhang is now 60mm from the ground. Worse yet: we have a massive balance issue:

However, if we move the housing for USB ports to the middle-ish of the base, we get the balance. Our base is now 4cm tall instead of 5 or 6. Battery demands, at most, less than 2 cm of overhang. Of course, the question is — what’s the price?

The answer: we now need to have the rock part of the base in two parts.

Or do w—

Actually yes, we do. There’s no way the battery is gonna fit through the 45mm (inner diameter of base) hole without having the rock in two parts. The good thing is that we can hide that, probably, by strategically placing our split.

But let’s design the rest of the base first.

Designing the Rock Formation

Designing a rock in CAD would be … functionally impossible (at least given our time and patience limits). There are programs better-suited to this endeavour, and they fall into the category of 3D modelling software.

I’ve tried using Blender for that purpose once. I wasn’t very impressed. Sculpting a 3D object through a 2D screen takes a bit of getting used to, since the way you imagine the object to appear while watching your monitor is — when you’re a complete and utter beginner like me — often not the way the object is shaping up to really be. I imagine 3D modelling is something that VR is great for.

Actually, I don’t have to imagine — I have a VR headset. Unfortunately, Blender (as of November 2022) does not support VR (although there is a plugin that allows you to view 3D models), meaning we’ll have to try and find alternative programs.

Running through our options

This sub-chapter will be a bit of a detour. It’s less about designing the base and more about complaining about our options.

GravitySketch

Is free (asterisk: auntie Merkel and uncle Scholz footed the bill, along with daddy Macron. Seeing EU fund useful stuff is nice), and it’s surprisingly good for quickly converting your ideas into 3D sketches.

However, it’s not proper sculpting software — and while it’s certainly competent enough to help me sculpt a model for a rock, I want to find something that is.

Fortunately, I have a friend who boasted with his Steam Sale find during a steam sale. I decided to follow suit. End result? Complaints from my wallet plus Kodon and Shapelab in my library.

Kodon

On paper, Kodon sounds like a better option. It supports both VR as well as desktop use, which is something that makes me instantly want to like it. Imagine this: you have a program that you can use on your main PC while at home, as well as on your laptop to show (or even mildly retouch) your shit while on the go.

But the excitement ends with the tutorial, because there’s a bunch of annoyances that got me real fast:

1. You can’t import STLs. You can’t import things from disks or partitions other than C.²³That’s mildly inaccurate: you’re limited to whatever disk holds your Documents folder. If your Documents folder is on a different disk — say, F: — you will only be able to im port things from the F drive..
2. The lack of tooltips on tools is infuriating
3. Good lord it’s very crash-happy, and the user interface sometimes doesn’t appear to work at all
4. Some tools don’t work the way you’d expect … though not that I’d know what a tool was supposed to do, given the lack of tooltips or descriptions on the icons.

Granted, the crashing seems to happen because the dwarf model that I imported isn’t exactly small, but Shapelab appears to handle it just fine. Speaking of which:

Shapelab

Appears to have less features on the tin, but at least it works? The controls feel much more intuitive to me (your mileage may vary — the person who pointed me to these two has the opposite opinion), though admittedly it lacks having “smooth” and “invert” buttons directly on the controller. It also doesn’t do voxel-based tools (at the first glance), but at the end of the day it was easy enough to get into. It also imported the dwarf STL without me having to convert it into an .obj file first, which is … pretty neat.

I think I’ll take Shapelab for now. After a couple of hours, the base is done:

Blender

With all parts of the base done, it’s time to jump into Blender to put them together, and do the final touch-ups. At this, we need to:

• Create a hole for the circuits in the base
• Hollow out the runestone
• Cut out a hole for slotting in the battery

Furthermore, back at the time I intended to have the dwarf on a 25mm base that slots into the main base, as this would allow me to use the mini in D&D games. This was later abandoned, when super glue turned out to be super ineffective at keeping the dwarf on the base.

Here’s roughly how the parts fit together:

I also had to correct (re-scrult) some parts of the 25mm base and quickly learned that Blender doesn’t appear to be able to automatically subdivide surfaces when needed while sculpting. Annoying.

At very late monday evening in the week of the deadline (1AM on tuesday), I’m done. Can I get the prints by Thusrday?

The print, painting, and assembly

… so obviously yes. While the outer base was printed with resin, the choice of materials for inner parts (electronics holder and battery holder) didn’t matter. Therefore, these parts were printed on FDM 3D printer with PLA.

Painting went without much problems (except the part where it took a long time). Snow was a little bit harder, as it was slightly too liquid. The real difficult path was with soldering things together and putting the finished thing into the base.

The base space had enough space for battery, power bank circuit, Espruino (microcontroller), and wires. However, at the last minute, I decided I don’t want to solder the wires directly to the microcontroller. This added a few headers and another PCB into the mix, which ate up more space than I had. Not too much though, and since the circuit tube was printed with PLA, I could make enough additional space by taking soldering iron to the screw studs.

This was enough to just barely fit everything into the base.

Here’s some additional photos:

After the circuits were done, it was finally time to program the lights to change colors at random intervals. This is the boring part, so we’ll just skip to the end.

End result

It didn’t win the contest, but it looks nice.