Hi there! I'm having trouble sending an email to you regarding your question re: teacher's tack, so I thought I'd comment here!

Teacher's tack, or, one of the brand names here is called Plasti-Tak, is a "re-usable adhesive, sticks to any clean, dry surface, never dries out. Safe, non-toxic. For use on posters, Christmas cards, area rugs, also cleans typewriter type"... it looks like this:

http://www.educationstation.esc2.net/images/Store_Pictures/sticky%20tak%20for%20wall.jpg

or:

sticky%20tak%20for%20wall.jpg (JG Image, 244x448 pixels)

and you can pull sections of it off and form them... kind of has the elasticity of gum that's been chewed for awhile (ew!). I use it for lots of stuff, and usually it doesn't leave behind a greasy residue. I even formed it into little 'stands' today to put lobster finger puppets on so I could photograph them.

Hope that answers your question, & hope all is well in Switzerland today! :-)