Well I don't really have the tetrahedral version and I thought that I could design it as sort of an add-on to the original skewb. The school I addend has recently acquired a MakerBot printer so I thought that I could design it in sketchup and print my own version.
If you could measure your skewb that would be very helpful. It also doesn't matter what size cube you have, because I am able to rescale it after the design is finished.
Also, the picture you see above is just I rough sketch that I made and is not very exact.
Interesting idea, however I don't really think you could make it as an add on because every piece of that design is different from the pieces on the original Skewb. The only part you could save is the core, and that's about it. I'll try to measure the dimensions soon though and provide you with them. Also, the above picture is actually a drawing I made.