Yesterday I made a Rubik's Magic with 16 tiles, by stringing together two ordinary 8-tiled ones. I used an old black Matchbox Magic, and a new red OddzOn one. If you string them together with the red one on the left of the 2x8 rectangle, then the rings on the other side can be solved as well (the 4 central tiles are already correct on other side when in rectangle shape).
I found that the easiest way to string the tiles is not to build it directly as a rectangle, but to build it in loop shape. When finished you just fold it open. When you take the two magics apart do not cut any strings, because you can re-use all the string loops to build the large magic. To build it, start with one tile, and use 4 of the string loops to add two tiles onto it. Repeat the process, adding two more tiles each time, making a long strip of tiles. At the end, add the last remaining loose tile and the tile at the other and of the strip to make your tile loop.
A few points to remember.
- Make sure you join the right tiles in the right orientation.
- The new string loops go through the same grooves as the loops on the tile you are joining to.
- Use sellotape to hold the tiles together at first.
- Try to put the metal joins of the four string loops on the four different long grooves of the tile you are joining to.
- After you placed one loop, place the next loop along the same groove, but make sure its wires cross in the opposite direction. The connections between to tiles will then consist of two lines together in the middle with two lines going one on either side of them.
It took me about 3 and a half hours to do this.
One pair of wire loops looks like this:



and the other like this:


