I've learned a lot from reading this forum so I wanted to give something back to the community here. This is my modified Barnett Strike Nine. It's an 'everyman design' meaning I hope anyone - anywhere - can try it out.
Barnett Strike Nine - $9
8mm (internal dia.) steel collars - RS Stock No. 122-3450 - $4
6mm rubber end caps - eBay etc
1. Unscrew the grip and reverse the frame. This is very important because it means if the collars do let go they won't be coming back into your face.
2. Attach the bands of your choice using the collars and a hex key. The bands wrap back over the collars when drawn.
Shown fitted with 20-15mm taper 0.58mm GZK bandset. Thanks, Griffo.