|: Those copers are cool, I have never seen anything like them before! is it still possible to buy them?
I don't know. Copers where quite common in the old days.
: I see how you get the sliders to stay in place.
: Ideally, i would like to use sliders instead of jumpbars altogher but I cant figure out a clean way to attach them to roller skate plates, with out the jump bar to tie it to.
Drill holes into the base plate and use screws. For my own (imperfect) way of doing this, see my article on how to build a vertical roller skate. Of course, I didn't user standard roller skate plates.