Magnets & Pin Needles
Alternative to magnets
Washi / Removable Tape (aka Post-It Tape)
Instead of magnets or pin needles, we recommend using Scotch's removable adhesive strips. They contain the same adhesive as Post-It's. I.e. the adhesive tapes hold on all smooth surfaces and can be removed even from paper without residue. They can easily be moved later (like Post-It Notes). If you are interested, you can find the tape under the following link or in the various office material online shops.
For Kanban boards we recommend you to use the Washi Tapes from 3M. We have used them excessively and can only report positive experiences. They are available in many colours and can be removed without leaving any residue. Available at 3M or in the various office supplies online shops.