I tried my hands at making a design similar to a Brams M5 caliper and it isn’t turning out as well as I had hoped.
Brake Caliper Design 2 pic 1
The good:  This design allows for easy manufacturing of the calipers.  Specifically, machining these arms will be a breeze on any mill.  There is plenty of strength in this design,  there aren’t any sections that are weak.

The Bad: Heft!  the bare caliper without any hardware comes in at an estimated 120g.  That’s plain-Jane brake weight and totally not worth pursuing.

There is a bit of hope though and it involves quite a bit of work but it might be interesting enough for me to try it out.  I will update when I am finished experimenting.
Brake Caliper Design 2 pic 2