I’ve been on a wild tear adding french cleats to my workshop and garage walls. I’ve been experimenting with various designs and have pretty much settled on this design for mounting dowels (1/4" and 5/16").
You can easily fit eight of these on a single sheet of plywood.
BTW, this is one of those rare cases that I recommend using cheap 1/8" ply from the big box store – “GoofGrade” makes this project quite inexpensive – I can knock out 8 holders for ~$3.50 and 30 minutes of cutting.
Use at your own risk. Not for commercial use or resale.
Great question - the vast majority of cleats are 3/4” thick. The height varies depending on the material used and personal preference. Given the price of plywood these days, I’ve switched to simply ripping pine 1x6s on my table saw set to 45°.
Rather than designing a custom cleat for my 18ga brad nailer, I created a spacer that hold two of the dowel mounts exactly 3" apart (dowel center to center). Intentionally tight fit, requiring a few taps from a mallet to lock in place: