I decided to make my Boyfriend a companion cube for x-mas, so I thought I'd share how I did it. Message me if you want .stl files.

Step 1: 3D Modeling & Printing

I split the companion cube into two pieces for easy printing(picture 1), and connected them with 4 dowels on the bottom face. The holes for the rods were 0.75in and the rods themselves were 0.75in-0.15mm. This provided a tight fit for the rods and give them no wiggle room. If you want to, you can add superglue before fully putting the two pieces together, but it it not necessary. Make sure to do it before the pieces are fully put together, because they will not come apart afterwards.

Next I made a stencil so I could easily air-spray on the hearts in the center(picture 2).

Step 2: Finish It Up and Paint It

If there are any unwanted gaps, use wood fill to fill them in and then sand it smooth. Then sand down the entire seam so it's hardly noticeable.

Painting materials
-Frog tape(or masking tape)
-Airbrush setup
-Rustoleum Primer
-Black, white and red acrylic airbrushing paint
-Finish brand floor polish or Krylon Crystal Clear top coat

1) Use your air compressor to blow off any small dust particles from the cube

2) Spray a couple light coats of primer on. Make sure you follow the directions, and don't miss any spots.

3) Mix your paints to achieve the white, grey and pink colors of the cube

4) spray light coats of your grey acrylic paint over the entire surface until it is sufficiently covered, and no black can be seen..

5) After it is dry, frog tape the entire surface that is grey on an actual companion cube so no white leaks onto it.(I will add pictures when I paint it)

6) Now spray on your white paint until no grey can be seen.

7) Let that dry and now use your stencil you've just printed out to spray on the pink hearts. Use newspaper or more tape to make sure none of the pink gets on the white parts.

8) After that is dry, use your airbrush to brush on light coats of Finish floor polish, or spray on the Krolon Crystal Clear for a glossy top coat. This step is necessary to protect the paint

Step 3: LED Cube Variant.

If you want to make a cube that lights up, you'll need translucent filament or resin to print with.

other materials:

-4 -- 5mm Full color LED from Radioshack

-1 -- 60 or 100 Ohm resistor

-1 -- 150 Ohm resistor

-1 -- 3v button cell

-1 -- button cell holder

-1 -- spst switch

- Wire

-Soldering kit

-Hot glue gun

Directions:

* print out all of the files below. You will have to clean it up for it all to fit together nicely(I'll upload them shortly)

*print out the Lens file in translucent plastic

1) Cut off the green lead on all 4 LED's. It'll get in the way. and cut the other 3 leads to .6in in length.

2) Solder a bit of wire on one side of the switch, connecting it to the positive side of the battery holder

3) Solder another bit of wire connecting the other side of the switch to the common anode(longest leg) on all 4 LED's(there's only 3 in the picture)

4) Solder one side of each resistor to each other, and solder that to the negative lead of the battery holder so all three are connected directly.

5) Solder the other side of the 60-100 Ohm resistor to the Red lead of all 4 LED's

6) Solder the other side of the 150 Ohm resistor to the Blue lead of all 4 LED's

7) Insert the battery into the clip and hot glue the switch to t corner in the half of the cube with the missing heart on one end, making sure there's still room to insert the heart cover

8) Hot glue the battery to an adjacent corner. You should be able to easily stick your finger in the hole and flip the switch and remove the battery when it needs replacing.

9) Paint the cube

10) When you are satisfied, pop the lenses, use glue on the edges if necessary.

11) there is a hollow hole covered by one layer of plastic at each of the four corners. rip off that layer and Insert the 4 rods into the holes at each corner of one half of the cube.

12) shove the other half on the other ends of the rods and push them together.

13)use wood fill and sandpaper to make the seam unnoticeable and paint over that area again. be sure to not get paint on the lenses.

14) Flip the switch, place in the heart into the hole and turn it counter clockwise until it locks in place