Being addicted to anything to do with Rubik's
Cubes I wondered if it would be possible to transform a skewb in such a way that it resembled one. After a few rough sketches I realised it was possible, at least from some angles and made this in 1996.
I originally called this The Slab but later changed the name to Mental Block. Mini Skewbs were not available at the time so I had to make it from a full sized Skewb. That is why it is so big. When Mini Skewbs did become available in later years I couldn't be bothered to start all over again with a small version. Plus I had gotten used to the very smooth rotation and clicking of the ball bearings which would be lost on a smaller one.
To make it I first sculpted the two new masters from solid polyester resin. This was done using a saw, files and sand paper. I did not own a Dremel until many years later. I then made moulds in remeltable rubber (Gelflex) and cast the pieces in polyester resin. As with several of my puzzles the first ones were very poor but in later years I improved the masters so subsequent castings were better. For many years it was a very heavy puzzle though with excellent movement. This combination had a bad side affect which it shared with my Golden Cubes, Container (large) and Giant Skewb. If the puzzle is casually picked up in one hand it will almost certainly be dropped. The pressure of the gripping hand causes a move/turn to start on the puzzle. As this unexpected move continues the hand is no longer actually holding the puzzle and unless caught very quickly it will be dropped. I can remember showing these puzzles off at various Dutch Cube Days and constantly telling people to use both hands. Usually they would look at me as if I was mad before they fumbled and dropped it back onto the table. I know of more than one person who have smashed them after getting them safely home. And it wasn't from frustration.
After a number of years (not continuous) slowly improving the masters I finally decided on a completely different approach. This was at a time when I was getting pretty fed up with moulding. I was still using remeltable rubber and polyester resin. Both of which are unreliable and dirty products to work with. Anthony Greenhill on the other hand had perfected a new way of making puzzle transformations. He would use some sort of plastic card and built little add-on boxes. This resulted in very accurate and light weight puzzles. However it can be a lot of work especially if weird shapes are required. It was perfect though for my cuboids and not bad for my Mental Block. So from then on I only ever made Mental Blocks from high impact polystyrene plastic sheet. Now they are much lighter and they no longer suffer from the dropping problem. At last I was making really good quality Mental Blocks.
On the earlier ones I used Skewb style textured stickers on the two opposite large faces and regular Rubik's Cube type on the other four sides. On my more recent ones I used regular Rubik's Cube style on all six sides.