I recently bought Aircraft Bases with magnetic rods.
I based the resin bases on to card to give them more stability with the heavier 28mm Eureka G-cars.
I painted the resin base with a dark earth colour and then with PVA glue, glued sand and fine rocks to the base. I found these looked good enough for African terrain, without painting. I later glued dry grass to the bases.
You will have to buy washers to glue to the bottom of your aircraft, so the magnetic end can attache to it. I struggled to find smaller washers in B&Q but I will try a local hardware store next for my smaller aircraft.
Extract description from the S & S Models site for this product:-
There are quite a few gamers who like to have their aircraft flying over the table so we designed these bases.
They are made to look like a tree stump and have a 9mm hole drilled in them to accept a standard telescopic & magnetic rod from one of those magnetic pick up tools often found in car tools shops for picking nuts ect from inaccessible places.
Magnetic rod supplied