Book binding tape. Flexible, archival (supposedly), designed not to crack or break over time. Probably will leave a sticky residue that may or may not be removed with a solvent. I believe it's available in cloth and linen.. I'm not talking about the clear stuff or paper tape used to repair pages, i'm talking about the stuff used to bind books and repair bindings. Pretty handy stuff, not sure just how different it is from gaffer's tape, except that it is probably thinner and comes in a lot of pretty colors.