Quoting --R.K. Blast--
Yes there are differences, however the basic design is still his. I too use his Tumbler design with my own modifications, however I always give him credit.
That must then be a coincidence. Yes, I made a Tumbler a year ago based on his design, but this version is not, I assure you. I can send you the LDD file if you like, so you can have a look for yourself.