This is my first Instructable, and my first entry into a competition! If you like this instructable, please vote for it in the Instructables Puzzle Competition, thanks!

I designed this puzzle a few months ago in Solidworks. While it was my own independent idea and design, I later learned that this puzzle has been made before, under the name of the "Rhombiminx", so I'll give a little bit of history about it before I go into how to make one.

From the TwistyPuzzles Museum:

"The Rhombiminx was originally built in 2003 by Laurent Blanc from a modified giant Rubik's 2x2x2. In 2008, it was independently designed and built by Garrett Ong using a modified Eastsheen 4x4x4 mechanism and cast tips parts made from handbuilt masters. Later on a second version was built using FDM printed master parts for a more precise build. In April 2009 a mini version was built using a mini Eastsheen 2x2x2 core and molding/casting. From the solving point of view the puzzles behaves like a 4x4x4 which contains just face cubies. The version from 2008 sold for 205 USD."

As far as I know, this is the first Rhombiminx that (besides the mini 2x2 core) has been completely FDM 3D-Printed. In this Instructable, you will learn how to prepare, print, assemble, and sticker a rhombiminx of your very own!

Step 1: What You Will Need

Tools

FDM 3D Printer (I used a printrbot simple meta, but any model printer should do)
Hot Glue Gun

Materials

PLA 3D Printer Filament
Hot Glue
3x3x3 Rubik's Cube Stickers
Xacto Hobby Knife (or scissors)
Eastsheen mini keychain 2x2x2

.STL Files

Print 8 copies of Rhombiminx_Filleted_1.stl
Print 24 copies of Rhombiminx_Filleted_3.stl

Step 2: Print Mini 2x2 Extensions

I sliced each piece I printed in Cura on default settings for my printer (15% infill, .125mm layer height, 45mm/s..) but any decent setting should work.

After printing 8 of Rhombiminx_Filleted_1.stl, remove the keychain from your mini 2x2, and glue each printed piece onto a differerent corner. Just a dab of hot glue on the printed part should be fine. Press and hold each piece onto its respective corner, and once the glue sets, make some turns on the 2x2 to make sure that the glue hasn't restricted any movement. Repeat until you have something that looks like the image above.

Step 3: Print Extended Faces

I printed these on the same settings as the base extensions. Since there are so many pieces, I printed them in 3 different colors total, with 8 in light brown, 8 in blue, and 8 in black. I think it would look a bit better all in one color, though. (Ignore the stickers on the pieces in the next few steps, since I didn't take pictures I was happy with during the first round of assembly, I ended up disassembling the stickered puzzle and taking pictures as I reassmbled it. )

Step 4: Assembly

To assemble this puzzle is pretty intuitive, you will need to gather all of the pieces you have printed so far. The pieces should just snap into place if you push them into the preexisting slots in the printed base pieces. See pictures above for reference, I'll try to add more later.

Once you are all done, you should have a functional rhombiminx! Make a few turns to test it out. You should have a fully functional puzzle with 4 turnable layers on each axis, and in the shape of a Rhombic Dodecahedron (arguably the best 3D shape ever). Test its functionality, turning as much as you can. I spent a day or two breaking it in before I stickered it.

Step 5: Stickering (extra Step)

My method of stickering this puzzle works if you just want to have stickers on your puzzle to solve it already. But if you really want the nicest stickers possible, measure your puzzle and send the dimensions to Chewie's Custom Stickers or Oliver's Stickers, both are online businesses that specialize in cutting Twisty Puzzle Stickers, I have ordered from both in the past and can vouch for the excellent quality and service of each.

Since I'm more interested in this puzzle as a fun solve than a showpiece, I just cut the stickers from 3x3x3 stickers, or normal Rubik's Cube stickers. I would recommend buying a new sheet of them online. Using an Xacto Hobby Knife or something similar, cut each sticker in half, then shave a little bit off of the hypotenuse to get the right shape. Apply 4 of these new stickes to each face, in any colors you want, and, voila, you have a fully stickered Rhombiminx.