The Wargames Table has a very useful article on making magnetic basing. Using a magnetic system can be useful both for movement trays and for transport.
For my part, I base all of my 28mm figures on one inch washers. Then, I line both movement trays and transport boxes with magnetic vinyl, of the sort used for signs for the sides of cars.
I’ve also found that I can paint the magnetic vinyl with no loss of magnetism. So, my movement trays have a green surface onto which the figure bases stick.
Source: miniaturewargaming.com
