Step 1: What you will need
A Rubik’s Cube (authentic or fake)
54 Uniquely Shaped Metal or Plastic Tabs (more on this in how-to)
A Razor Blade of your choice
2 Part Epoxy for use with plastic/metals
Toothpicks or like for mixing/applying epoxy
Step 2: Obtain Rubik's Cube
Any Rubik’s cube will work for this project. It is estimated that over 300 million authentic or knock-off Rubik's Cubes exist. This should cost (at time of typing this) around $10 for a new authentic Rubik's cube. However there are a TON of them on E-Bay for much cheaper.
Step 3: Obtain 54 Round or Raised Square Metal Tabs of 6 different raised shape designs
If using an authentic sized Rubik’s cube, these will need to be smaller than 5/8th is of an inch square, and preferably no deeper than 1/16th of an inch (or the cube will become noticeably cumbersome in size). If you can only find 5 shapes, remember that a single side missing shapes is still an identifier (provided all other sides have identifiers). Other options (not as cool looking in my opinion) are sandpaper, wood, cardboard, plastic, etc. Scrapbook or craft stores might be a good place to shop for something like this.
WARNING 1: The Designs must FEEL different from each other. Each shape needs to have a distinguishing characteristic to differentiate it by touch rather than sight. THIS IS IMPERATIVE.
WARNING 2: It is best to ensure that each of the 6 shapes is quadratically symmetric* in design (i.e. turning the shape 90 degrees yields same design as before turned). This ensures that after mixing and solving... the cube looks complete (note that one of my shapes does not follow this rule).
Many who are new to Rubik's cubes are unaware of the fact that if you were to draw arrows on each square of the cube when you buy it, solving it to perfection is not as easy as some pieces will not be soundly placed (arrows in all same directions). Please refer to the picture for reference. Unless you know how to solve a cube like this, you will want to ensure the designs on the tabs are symmetric as mentioned.
Step 4: Peel Stickers off Cube
The author used isopropyl alcohol remove left-over adhesive. The stickers are a TWO-PART sticker in that the color is covered by a second sticker of Clear-coat (this may not be the case in non-authentic or legacy Rubik's cubes). So make sure you get both.
Step 5: Etch the cube in prep for Epoxy
Using your choice of a razor blade (careful!!!) etch the center of plastic squares with 8-way cross-hatch so that Epoxy will hold better to the etch than just the smooth plastic (this may not be necessary if the glue you use bonds to the plastic).
Step 6: Etch back of metal tabs/pieces
Using your choice of a razor blade, etch the backs of the metal tabs with an 8-way cross-hatch. To do this safely, lay a piece of duct-tape upside down and used two pieces of right-side -up duct tape, and laid the tabs down accordingly, then etched the back with a box-cutter knife with a new blade.
Step 7: Clean cube and tabs with alcohol
Clean backs of tabs and surfaces with isopropyl of alcohol. This will help to ensure the bond will not be affected by fingerprint oils and any other foreign materials.
WARNING: This will not harm an authentic Rubik's cube. If your cube is not authentic it might be made from a form of Acrylic. If this is the case either SKIP THIS STEP, or use soap and water and let completely dry. Alcohol would melt/crack/damage your acrylic cube.
Step 8: Epoxy pieces to Cube
Using a 2-part epoxy, bond each side of 9 shapes to the cube centers. Use as little as possible, but ensure a complete bond.
NOTE: Gorilla Glue, but did not want to clamp these down (a necessary step requiring clamps I did not have). Also, Gorilla Glue expands 3 times and if not used carefully will look messy.
Step 9: You are done! Metal Rubik's Cube complete.