Open Dungeons

I play a D&D game. We recently transitioned into playing in person (yay vaccines!) and after much discussion, we have acquired a 3D printer.

Blame my friend Jan.

Anyway. One of the things I wanted to build, besides maybe minis, was the modular dungeon! I knew about the brilliant Devon Jones and his OpenForge dungeons, and recently he’s pushed out a version 2. This was exactly what I wanted and needed. The problem … all the tutorials were for version 1. So I had to sit down and figure out what I really needed.

What’s OpenForge?

OpenForge is an open source (heh) dungeon set for D&D which lets you build…. oh this:

Example build by the creator – Devon Jones

Originally we used images on a screen, or (badly) drawn lines on a mat. And all my D&D life, we used graph paper and ‘theatre of the mind.’ We’ve also been playing online for almost a year, and now that we’re in person, I find myself wanting minis and a set for people too SEE the evil that is in my mind.

What Connections

There are three main types of connections:

  • Magnets – Most common, it lets things be compatible with Dwarven Forge
  • OpenLock – this is a kind of lego-esque clip connection from Printable Scenery. It’s open source.
  • Dragonbite – Proprietary (licensed) but compatible with their system
  • Infinitylock – Compatible with the DungeonWorks system
  • Glue – … As it says.

Magnets are a little weirdly expensive, since you have to buy the magnets to go in. Glue is messy. What I wanted was OpenLock — it’s more stable and my supplies are upstairs.

Originally I was really anti-glue, but as time went on, I came to appreciate it. Especially since I can throw things in the freezer to separate them! But day to day I wanted to be able to click things together like lego and change up sets when needed.


The next bit is where I got miles of miles confused. Here are the recommended starter sets for the Stone setup. I figured stone is 90% of what I’ll be using for now (there are other places where we may be on mats, like for the beach or wood battles (yes, beware players! More adventures are coming!):

Stone Floor

  • 16 dungeon_stone_floor.inch.E
  • 8 dungeon_stone_floor.inch.F
  • 2 dungeon_stone_floor.inch.R
  • 4 dungeon_stone_floor.inch.U

Stone Walls

  • 20 dungeon_stone_wall.inch.A
  • 4 dungeon_stone_wall.inch.BA
  • 8 dungeon_stone_wall.inch.G
  • 2 dungeon_stone_wall.inch.IA
  • 4 dungeon_stone_floor.inch.Q
  • 4 dungeon_stone_column.inch.I.stl
  • 8 dungeon_stone_column.inch.L.stl
  • 4 dungeon_stone_column.inch.O.stl
  • 4 dungeon_stone_column.inch.X.stl
  • 4 dungeon_stone_column.inch.T.stl

If you look at that, though, you wonder what the heck E, F, R and U are. Oh and then there’s Openforge vs Triplex!? And some of those files have SIDE in there!?!


First, we’ll cover the bases. Depending on how you want to connect, depends on the base you want. The one we’re going to use is triplex – which has many openlock ports, one per edge between squares and one per square. So here’s what Triplex looks like:

The non Triplex is just a ‘topper’ which you will then glue or magnet on to your bases (hence why I came to love the glue). The Triplex comes with holes on the sides, which are for using OpenLock clips! That said, you will need to prep your printed whatnots for the clips. Which is also a pain in the ass.

This means I looked at the toppers and then I looked at the bases. There were a lot of options, and I finally settled on the one that had the least amount of work for me: OpenForge 2.0 Plain OpenLOCK Base

Related to that, the ‘side’ versions of walls are ones with click holes on the sides, as well as front/back.


I like this. It’s a double ended clip you stick in the holes in the above. They look like this:

Photo of Springy OpenLock Clip by Marcel Toele

Stick ’em in the hole, click and done. Now if you don’t want to use the clips, you can put magnets in some of those holes. If you’re using OpenLock, you want about 2 clips per tile you print, so 54 for the starters. For magnets you’ll need 256. Big difference!

Many people recommend the Springy OpenLock Clip by Marcel Tool, who makes a loose, medium, and firm springy version (he recommends the medium). For whatever reason, I could not get it to build properly reliably (sometimes it was okay), so I used the ones made by Jones and the official ones until I could figure out why my slice was wrong (I’m very new at this!).


Now! What the bell end does “dungeon_stone_wall.inch.A” mean?

Well after some serious digging I found the documentation about filename! [Texture]#[Shape]+[Shape Options].[Letter].[Connection system]+[Options].stl

Now… that’s the new naming convention, but as you can see on Thingiverse, the names aren’t that. But! That clued me in to the fact that those letters, A and AS and so on all relate to the OpenLock code!

This is made worse by the ThingiVerse display:

If you hover over the name, you can see the whole name but you cannot click on the small picture and see the big one. I had to turn off ‘max width’ to get the full names, and everything looks like this:

  • dungeon_stone_floor.inch.AS.openforge.stl
  • dungeon_stone_floor.inch.AS.triplex.stl

Obviously I don’t need openforge AND triplex. But that still was a pain in the butt to get the list of. And those tiny photos meant I was going mad to figure out what the hell was what Thankfully someone else felt my pain, and with that I made a key!


AS3″ x 1″ rectangle (wide)
E2″ x 2″ square16
EA3″ x 3″ square
F2″ x 2″ curve/V8
I1″ x 1″ square
R2″ x 4″ rectangle2
S1″ x 2″ rectangle (tall)
SA1″ x 3″ rectangle
SB1″ x 4″ rectangle
U4″ x 4″ square4
# means the recommended number to print from the starter set

That makes a lot more sense, right? I tend to use sprawling dungeons and large rooms (they’re fighting in the castle as I started all this) it would work for me. Except for the 8 F’s. I don’t use curves like that because I’m hand-making maps and I hate curves. I can’t make straight lines.

Walls are a little weirder since a number of items have ‘side’ options and ‘pegs’ options.

A0.5″ x 2″YesYes20
B0.5″ x 1.5″YesNo4
G0.5″ x 2″ x 2″ curved cornerYesYes8
IA0.5″ x 1″YesYes2
Q0.5″ x 4″YesYes4
I1″ x 1″NoNo4
L1″ x 1″NoNo8
O1″ x 1″NoNo4
X1″ x 1″NoNo4
T1″ x 1″NoNo4
# means the recommended number to print from the starter set

You’ll notice new columns!

  • Pegs is if there’s an alt version with pegs for making a second layer (not needed for starters)
  • Sides is if there’s an alt version with clip slots on the sides

All columns are 1″x1″, but have pegs in different places.

What did I Print?

The weird part about this was figuring out if I really wanted Triplex (supports all three) or just plain bottoms and glue on tops… I will likely use the same floors over and over and over again. And I don’t plan on stacking layers…. Yet. Not until they have fights in a house. Otherwise I’ll pop upstairs, get the next set, and pop back down and have them scream their delight at me.

So what did I end up building?

  • 54+ OpenLock clips — these are a mix of springy and official and Devon’s
  • 36 2×2 bases (E) — these are a mix of topless (10) and the old plain ones (26)
  • 16 2×2 curved bases (G) – topless
  • 2 2×4 bases (R) — topless
  • 8 4×4 bases (U) — topless
  • 16 cut stone 2×2 toppers (E)
  • 20 cut stone 2×2 walls (G)
  • 20 cut stone 2×2 wall floor (G)
  • 4 cut stone 4×4 toppers (U)
  • 4 cut stone 4×4 wall floor (U)
  • 4 cut stone 4×4 walls (U)
Example of how to do an interior hallway by Manfred G

You’ll notice things are more than they recommended. Once I went with toppers, while it does mean a lot of gluing, it also let me use the new Wall Floor system, which obviates the drama of a wall being a half inch. Instead of having a half-inch gap between wall and the floor behind it (like if you’re doing internal walls), you can make a wall that takes up a half inch, and then a floor for an inch and a half.

The example image I included is weird, I know, but basically those are TWO towne_wall.floor.inch.2x1, which are both 1 inch wide. Then two walls which are each a half inch for a total of three inches. Plug them onto an AS or SA (3 inches by 1 inch) and you have a hallway!

Since I’m building a specific campaign, I mathed out what I needed to mimic the boss fight. In the end, I decided to change the size a little from paper map to cardboard to real, to compensate for what I was doing.

I had to wait to post this until (a) the printer showed up and (b) I had successfully built the set. My wife knew I was doing this. The others did not. And due to the time crunch we did not paint them. Still… it worked! Here are some of the ones I’ve made (or am making) and a cardboard to compare:

So far, it’s all been well received.