I've made bookshelf label holders from thin acetate sheet by cutting
out a 7cm x 5cm piece, then lightly scoring and bending it to fit over
a standard 19mm shelf.

It works okay-ish as a bookshelf label holder, but it's not "springy"
like a real clip would be. Unfortunately, I have ~never~ found
suitable transparent clips/holders, which is why I make my own from
acetate sheet. (Okay, so there are these:
http://www.gresswell.co.uk/clip-on-s...FRG3GwodJfYD9Q
but (a) they're ruddy expensive and (b) they are too wide, meaning I'd
have to cut them into shorter pieces, probably with a fair bit of
wastage.)

Previously, I used transparent glue dots to fix my holders' "flaps" to
the over- and undersides of the shelf. These can't be seen unless one
looks really closely. But the downside is that you have to
painstakingly remove the glue dot residue from the shelf surface if
you want to move a holder.

So how might I make the bent acetate sheet stiffer? I tried with a hot
glue gun along the bend lines (after bending to a square profile), but
you can see the glue. However, the principle works! The resultant
holder is noticeably stiffer with enough "spring" to keep it in place
on the shelf without glue dots.

Chemicals? Vinegar? Salt solution? Something to spray on the holders
after bending, perhaps? Surely something must exist to make the
plastic more brittle? Obviously the clear transparency of acetate
needs to be preserved as much as possible.

Here is a picture of my holders, one in position on a pseudo
bookshelf. The glue dots are visible in the pic, but not so much when
you're in the room where the bookshelves are.
http://www.littletyke.myzen.co.uk/ac...bel_holder.jpg

Note that I have 70+ categories, so that's a lot of label holders!

Cheers!

MM