Thanks, I've been looking on Ebay as well, luckily there seems to be enough variety in diameter :)
I'm also thinking of using a bit of inner tube to put some extra protection on the corners underneath before finishing it off with the heat shrink tube, which would increase the diameter some more - I'm sure I'll find something that suits. Thanks again for the suggestion, it hadn't occurred to me at all.
Thanks, I've been looking on Ebay as well, luckily there seems to be enough variety in diameter :)
I'm also thinking of using a bit of inner tube to put some extra protection on the corners underneath before finishing it off with the heat shrink tube, which would increase the diameter some more - I'm sure I'll find something that suits. Thanks again for the suggestion, it hadn't occurred to me at all.