Attn TL and W & C

[NorthernRaider]

Guys I wonder if I could pick your brains and educational skills a bit.

I'm reading up about the Theraband stuff and crossbow mods both of you display some expertise in. It got me thinking about how easy could it be to make or modify an old crossbow, or to jerry rig thise theraband stuff to a rifle or bowstock and make something like a spear gun or high powered 9 mm ball bearing launcher that uses this super elastic rather than a fibreglass limb ???

I appreciate range would be reduced, but so would the bulk of the tool making it good for close quarters or indoor security stuff/

What do you two engineering types reckon ?