Glue
Blue tack is a kind of elastic putty that doesn't set but holds well and lifts away afterwards, can be re used. There is also white tack, same as above but white. Available at all good diy and craft shops. Lasts for years, I bought two packs in 2010 and still using, also ideal for sticking drawings up on workshop wall.
Fair winds and calm waters,
COLIN.
COLIN.