I use 3M polyester tape type 850 black. This tape is so thin, 0.05mm, that it does not bulk up the bellows even if you covered the whole thing. The tape is very flexible so it can be used to patch pinholes in the corners and then the bellows can be re-pleated easily. Best of all the adhesive is strong, doesn't bleed, doesn't creep, and never goes gooey.
The downside? It is an $$$ expensive roll of tape.
Photography, the word itself, invented and defined by its author Sir John.F.W.Herschel, 14 March 1839 at the Royal Society, Somerset House, London. Quote "...Photography or the application of the Chemical rays of light to the purpose of pictorial representation,..". unquote.
Gaffers tape is expensive, but it takes me years to go through a roll. I wind some on to a 120 roll film spool and keep it in my camera bag, very handy to have. Can be removed from most surfaces without leaving residue. I just bought a 5x7 Kodak D2, I have to check the bellows for light leaks. I'm inclined to try the E-6000 for any pinholes. If I had a tear to repair I wouldn't hesitate to use gaffers tape.
This is an older thread but I'll put in my 2 cents. Black bookbinders tape works very well on most any type of bellows. We not only used it to bind books but to repair holes/tears in the bellows of the big process cameras. Once stuck it never comes off and remains very pliable.
I'd be careful with gaffer tape. I've used it for temporary fixes (like attaching lights to whatever is available when there's no room for stands), and I've noticed that if you leave it on for a short while, no more than a week or two, it leaves no residue. But if you leave it on for several months, it does -- thick, sticky goo that's very hard to remove.
These people sell black liquid neoprene rubber in a 4-oz brush-on can. I've ordered some for bellows pinholes, but haven't tried it yet. It's actually manufactured by the Plastidip people and re-labeled by these dive shop folks as "Trident Neo Coat" (found that out by reading the MSDS sheets). Plastidip sells the same product but calls it "Liquid Tape". It even comes in a spray can (from Plastidip). Be careful about ordering liquid tapes and such, many are just a plastic vice rubber compound and won't be as flexible or last as long. This stuff is supposedly liquid neoprene rubber. http://www.dolphinscuba.com/ProductD...LP55&click=287