The Fridge Magnet Marble Run is a great toy for kids and big kids to stick on the fridge and play with. It was designed in prodesktop, and can be cut out with a laser cutter, using 3mm material. You can use marbles or coins, the coins will run much slower and require steeper incline than marbles, but still fun to set up and play with. A friend suggested I put a box at the bottom that you cant get into for the coins.
Most of photos have notes attached

Step 1: Stuff You Will Need.

Download the DXF
laser cutter
glue
hot glue gun
cast acrylic sheet or other material that is 3mm thick
10mm diameter X 3mm thick button magnets. can be purchased from ebay
cotton buds or small brush.
The 2 DXF files have the parts as shown one has 10 rails nested and the other has a one rail and one catcher.
A CAD drawing program would be useful if you want to modify parts or print on to paper

Step 2: Assemble

Assembly is straight forward, the only thing you have to watch is the to rails are different widths, the wide rail goes to the magnet side Once you have cut out the parts, just glue together with acrylic glue (I find a cotton bud good for this) Insert the magnets and hot glue into place. Make sure the parts are glued well, as kids like to drop things and the marble run will come apart or break if not glued properly. The final part has ends on it to catch the marbles. The magnets are quite cheap from ebay but you will have to wait awhile for them to arrive.
I also found it is useful to put a thin coat of silicon sealer on the magnet, to stop it damaging the surface of the fridge and to help give the a bit more grip as the runs tend to slide down the fridge door when the marbles do jumps

Step 3: Set Up and Play

In the photo I didn't have enough magnets so I blue tacked it to the fridge, The magnets I ordered off ebay are going to take a couple of weeks.
The marble run is a hit with the kids, I also plan to make some accessories to go with the run, so far I've thought of.