My final version of an elite strap alternative:

Advanced Strap

I tried to imitate the elite strap as closely as possible. i think the plastic alone is very convenient, but i added an optional padding! Simply print it with some flexible material an glue it to the inside of part 1.

8 screws are needed. I used some self-tapping screws 3 x 8, but metric srews should also work (thread cutting needed)

universal battery holder is the same as in my first design