3M VHB Double-Sided Mounting Tape
This is the good stuff: truly industrial strength foam tape that'll firmly adhere objects to glass, painted or bare metal, most plastics, even concrete. It's actually an alternative to nails, screws and welds in many applications. Far, far better than that white foam tape they sell at office supply stores. Expensive but worth it. A roll of this will last you a long time. $28.99 at Amazon.