Introduction: Pentomino Belt Buckle (3D Printed)

About: So many things to learn and make, so little time! I like things that are cool, useful, efficient, well crafted.

This is a playable pentomino belt buckle!

Transform a boring or worn out belt buckle into this geeky one!

Play pentominos on the go to pass the time when your smart phone battery died.

The special trick here is that the pentominos hold together thanks to their special structure on the edges, which even allows to turn a piece rear-side-front (chiral operation).

Step 1: Needed Stuff and Files

If you want to build this project, you will need basic experience with 3D printing, to re-generate the STL files in order to get the exact tolerance. This will be done in OpenSCAD.

You will need

- A worn out belt buckle, with a flat surface.
The one on the photo lost its matte aluminum-looking coating, and when sanded, would catch ugly corrosion spots ever again. So, it was classy, let's make it geeky!

- A 3D printer.

- The OpenSCAD free software:

- The Inkscape free software:

- Needed to prepare the existing buckle: sand paper, metal files, and optionally a drill press.

- Epoxy glue, plastic glue, clamps.

Project files

The project files are in the ZIP archive attached to this step.

You can also visit my repository on Github.

Step 2: Prepare Original Buckle

This step is really specific to the buckle that is used, and is here to give you an inspiration to prepare your own one.

The goal is to have a rectangular, flat surface, on which the frame will be glued later on. Also, the surface shall have a hole, so that you can push away the pentominos.

I have provided some files to make mine, in these steps:

3d-printed cover

1) Open 1-belt-base.svg in Inkscape:
This is the projection of the two layers. Modify as desired.

2) Generate the 1-belt-base-a.dxf and 1-belt-base-b.dxf files:
a) For each layer of the SVG file, copy-paste it into a new file,
b) File -> Document Properties -> Page (tab) -> Page Size (group) -> Resize page to drawing or selection,
c) Extensions -> Modify Paths -> Flatten Bezier,
d) Export as DXF.

3) Open 1-belt-base.scad in OpenSCAD. It refers to the two DXF files.
Render, and save as STL.

4) Print the STL. Bend with the rough surface inside, to be in contact with the buckle.


I marked the buckle using the cover's hole. Then with a drill-press and a 3mm bit, I bore the contour of the hole. Then with a metal rounded file, I cleaned the hole's border.


I applied some epoxy glue and clamped the whole during the curing.

Step 3: Print Frame

You will have to resize the frame so that it fits the existing buckle.

1. In OpenSCAD, open the file 2-frame.scad.

2. Adjust the value of H_SCALE_FACTOR.

3. Generate the STL file and print it.

4. Check the printed frame fits well on and around the existing buckle and its cover.

Step 4: Glue Frame to Buckle

Apply some plastic glue into the inner corner of the frame's border, affix to the buckle's cover and clamp.

Step 5: Calibrate Blocks

Now we will tune the model so that the pentominos fit "correctly" into the frame.

"Correctly" means a bit loose, so that they can be easily detached, but having enough grip so that they will not fall off the frame.

I noticed that filaments of the same manufacturer but of different colors seem to yield a slightly different tolerance...

So in this step we will scale the pentominos in the horizontal plane.

1. In OpenSCAD, open the file 3-calibration.scad.

2. Generate the STL file and print it.

3. Check that, when the frame is held vertically, the 3 pieces "just hold" as shown in the picture.

4. If not, change the parameter H_SCALE_FACTOR; bigger value makes larger pieces and vice-versa. Repeat at 2.

When the calibration blocks are okay, take note of the H_SCALE_FACTOR value and continue to the next step.

Step 6: Print Pentominos

1. In OpenSCAD, open the file 4-pentominos.scad

2. Set H_SCALE_FACTOR with the value found in the previous step.

3. Generate the STL file and print it. Note that the 3 calibration pieces are omitted, as they were printed in the previous step.

So now we have all pentominos.

Note that, thanks to the structure of the edges, they will stay together when held by the sides with a moderate pressure. See picture.

Step 7: Assemble

Solve the puzzle!

Assemble the pentominos into the frame.

Step 8: Finished Product

Print pentominos in other colors, and combine them.

Post your results, amaze your friends.

Thanks for reading.

Before and After Contest 2017

Participated in the
Before and After Contest 2017