I was thinking of helping my son hang the models we built with fishing line like I did when I was a kid, but he likes to play with them, and you can really only appreciate the bottom of the model (the most boring side IMHO) when they are hanging.
Equipment & Parts List
0.5" Neodymium Magnets with 90 degree taper hole
0.5" Metal Washers
4x1/2 Phillips Metal Screws
High Strength Glue or Epoxy (I used Household Goop)
UPDATE: Laberatory424 sells the magnets with adhesive already attached
Step 1: Get the Magnets
The washers I had already - and was happy to have silver and black. They need to be ferrous, so make sure they stick to the magnets before using them.
Step 2: Mount Washers on Models
Use a generous amount of glue and wait for it to dry completely.
Step 3: Screw Magnet Into Wall
Notice the metal screws I used protrude a little bit - this turns out to be a nice feature of the mount as it lines it up with the washer.
For heavier models I've also used a combination of goop + a screw into the wall.
You can also glue the magnets to the wall w/o any screws - but use a tack or tape to hold it in place as the glue dries or it might slide out of place.
Step 4: Stick the Model to the Wall
Step 5: Admire And/or Play
Notes: I originally planned on having magnet to magnet mounting - and also purchased some magnetic disks - however the magnetic bond was much to strong and would have made it difficult to glue the magnet to the model well enough that it wouldn't come unstuck.
I also originally planned on multiple mount points for each model - but the magnets were much stronger than anticipated and a single point works perfectly. UPDATE: I have since mounted a few models with magnet to magnet contact.