Trampa 3D concave extension

Use epoxy to stick it to the board. Mylar doesn't stick to epoxy, you can use it between the parts and your clamp (a simple potato chips pack will do the trick). The epoxy should go through the part and make it very strong.
I use TPU for this parts.
https://www.youtube.com/watch?v=ymlSxZU2Y1s

Got a HS11 deck?
Check this remix from Jonny1983:
https://www.thingiverse.com/thing:3227325