This design came about because I was trying to make something that looked like a Kumiki cube, but that had a 3 piece burr in the middle. I took the Castel, designed by Yavuz Demirhan, and used that as the base for the puzzle. I removed 2 cubies from his design to allow the pieces to work. This was the final puzzle after playing around with a number of others, and this was a significant increase in the number of moves to solve. Interestingly the 3 piece burr is still a single solution.
I am particularly pleased that the 4 double cube pieces are identical.
Eric Fuller made a similar looking puzzle designed by William Hu Called Band Cube, and I am sure there are other similar designs.