This is almost certainly the world's first twisty puzzle transformation (mod). After many years it is now in very poor health but it's probably the puzzle that lead to the hundreds of transformations being made today.
I made it when I was still at school during 1981. I was totally obsessed with Rubik's Cubes at that time and would spend hours solving them, thinking about the maths, the mechanism and pretty much everything Rubik's Cube related. When I picked up a few spare Cubes the idea came to me to join two together. I quickly realised that by cutting each in a certain way I could make the puzzle on this page.
I was very pleased with the way the puzzles appear to overlap one another though disappointed that there seemed no way to make the pieces move from one cube to the other.
When I made it I hadn't considered the fact that solving the puzzle would actually present new challenges. The solving required is easily simulated on a regular Rubik's Cube by bandaging (fixing) three adjacent cubies along one edge together. It quickly becomes clear that trying to solve this puzzle using a Rubik's Cube method is not quite good enough. I am not saying it is harder than a regular Cube, just different.
Later the whole subject of bandaged cubes evolved and people like Dieter Gebhardt spent a lot of time exploring different bandaging on different puzzles. He wrote numerous articles on the subject including at least one book.
In 1982 I was eagerly awaiting the release of the 4x4x4 puzzle. I often popped into my local puzzle/games shop and pestered the owner about this puzzle. One day he told me about a guy called David Singmaster who was at the time the UK expert on all things Rubik's Cube related. He told me how David would be at a games day in my local town.
On 1st May 1982 I attended the show and spent most of my time talking to David and playing with his many puzzles. I hadn't bothered to take my transformation because I didn't think anyone would be remotely interested. During the day though I did mention it to David and he was utterly fascinated. He insisted that I went home and got it.
After a very fast cycle home and back again we spent a lot of time talking about my puzzle. A member of the public walked by and said, "Oh look, Siamese Cubes". Up until then I hadn't named it and frankly had no intention to do so. David however loved this name so for ever more it was known as Tony Fisher's Siamese Cubes. David went on to write about it in his Cubic Circular magazine/newsletter.
After my puzzle appeared in Cubic Circular Erno Rubik produced the same puzzle calling it Rubik's Mate. To this day I still don't know if he copied the idea or independently came up with it. If he did copy it then I think I'll let him off this once. More recently Uwe Meffert produced it and over the years I have also made- Siamese 5x5x5s, Triamese 5x5x5s, Siamese 2x2x2 Triplets, Siamese Skewbs, White Micro Siamese Cubes and Siamese 6x6x6 V-Cubes in both white and black plastic.
You can purchase factory made Siamese Cubes below.