Search the internet for a Free Vector Fidget Spinner art.
Import in your favorite vector graphic program (I used Corel).
Draw 22mm circles (the bearings diameter).
Match the vector image bearings positions to the 22mm circles for alignment and creating the template.
Add center marks inside the circles.
Print the template.
Step 1: Paper Template
Cut your paper template. I like to use curved scissors for that.
Step 2: Time for a Sandwich
Get the chosen plywood or wood. I used 4mm thick laminated plywood.
> On a second run I used a piece of nice Brazilian Rosewood I had around.
Using the printed template, cut it to roughly the size you will need.
I using plywood, make a sandwich using two of them. I used 5-min epoxy with Micro Ballons (microscopic glass balls) mixed in, to make it easy for sanding later. If you don't have that, no problem, you can use other types of glue including wood glue, but that will take longer to cure. Let it cure under heavy weights over a thick glass to assure it will be straight and even.
Step 3: Get Your Bearings
Test fit the bearings to the template.
Decide which bearing will be the best for the center.
Take it's dust cover off (lots of videos of how to do it in Youtube) and use a solvent to remove ALL grease.
Leave the bearing totally clean and without any lubricants. But, I found out that graphite powder makes my bearings almost double their spin time!
Step 4: Tape It
Tape the template over the wood. Draw the outlines with a thick visible pen.
You will cut in the inside of the outline later on.
Step 5: Drill It
Using the template and center marks as a guide, start drilling the holes with a 3mm wood bit.
Then, put another piece of the same wood UNDER your plywood sandwich. Set it on your drilpress bench.
Carefully center your 22mm spade bit in the hole and CLAMP FIRMLY everything in your drillpress.
Drill all holes. Use 2000RPM speed for best results.
Step 6: Test Fit
Test fit the bearings.
Step 7: Saw It Up
Using a hacksaw or jigsaw, saw it inside the outline you drew it before.
Step 8: Sanding Time
Elbow grease step: first, I used a router to round all corners but you can do the same using a 80 grit sandpaper (takes longer).
Then, raise to a 120 grit sandpaper and sand it thoroughly.
Last, go for a 180 or 200 grit again.
> For the rosewood I went up to 600 grit.
I forgot to take a picture but after this step, clean the spinner and apply wood sealant at least 2 coats.
Let it dry, sand it with a 180grit and apply 2 more coats. Let it dry and sand it with a 600 grit, or 800 or 1200 to pull a nice shine up.
Do not wax it yet, you'll want to have a good inside surface in the holes for glueing the bearings.
Step 9: Starting to Look Good
Test fit again your bearings.
> For the rosewood, I decided the finish was going to be only Carnauba wax, since it is a very oily wood. So I masked the holes before applying wax, to avoid contaminating the surface in which I will be applying glue later.
For gluing the bearings, MASK your spinner leaving only the holes open, in both sides.
Clean the bearings then with isopropyl alcohol and apply a thin coat of epoxy glue to the outer side of each one. You might do one at a time to avoid the glue starting to cure.
Insert the bearings in the holes, wipe any glue excess with isopropyl alcohol, let them cure over a thick glass sheet to ensure they will stay even.
Step 10: Finished
Remove the masking tape.
Clean your spinner with a rag, wax it if you want it.
For the center cap I improvised using a Hard Disk steel shaft that fitted perfectly, and then capped it with LEGO pieces, glued in place. Will replace this with a commercial eBay magnetig cap later. I'm too lazy to make the cap myself now. :)
It came up pretty good, not 100% balanced, but...it spins for 1:05 most times. I reached 1:38 in some tests, so, it's pretty decent for a DIY, I guess.