I'd also like to address some common concerns: I went with a 3 wheel design because I wanted the bottom part that held the wheels to be a single, solid piece and a piece for three wheels was the largest I could print on a Makerbot Replicator 2. As for comfort I used some craft foam and packing foam in the boot and on the footplate and between it and my normal skate I couldn't tell a difference. I didn't include a 'brake' on the skate because of size constraints (a separate piece could definitely be added) and I've never used them as I feel toe dragging is a better stopping method.
To make this project you will need access to a 3D printer, or a company like Shapeways, as well as some general CAD knowledge for the program you will use (the tutorials they offer should be plenty). For these instructions I am using Autodesk Inventor 2013. Also make sure to wear the appropriate safety gear and use caution when testing! Most importantly, have fun and be creative!
Updates: Since building I have made a seconds skate and found that the toe part of the boot and the tongue are essentially only for looks so I updated my design without those and just added a little toe guard to the end of the boot for safety. All the files will still be on the thingiverse page.
The files for all parts can be found on Thingiverse HERE.