Needlefruit, I think a minimum would be 1/4 inch to 1/2 on each end.....plus curving and putting duck tape. I thought just painters tape, but the duck tape is much stronger plus a couple of layers wouldn't hurt.
I've just started making these and am working out the kinks so to speak to fit the gifts I'm giving away for Christmas.
DH has graciously given me 2 of the 'free' tapes from Harbor Freight [25 or 50 ft each], now I just need to snag a pair of his metal cutting pliers as I think mine are not strong enough. Hmmm or maybe give him a project he can do in his 'man cave'.