The next IPP competition puzzle I pulled out of Bernhard Schweitzer's 1st package is called HERMAPHRODITIC BLOCKS. It was designed and produced by George Miller more than a decade back and made its entry at IPP 2003. However, Bernhard had the same design idea already in the 90's and did share his sketches with George when he received this very puzzle the first time at an IPP exhange. I was very lucky that Bernhard had two copies and sold me one for 30 Euros.
We are talking about 8 small cubes which have 1 peg and 1 hole each on 3 sides. The goal is to assemble the 8 small cubes to get a big cube where none of the small cube sides with peg/hole can be seen from the outside. I could read on George Miller's hoempage (Puzzle Palace) that there is more than one solution to this puzzle and because all the small cubes have pattern on each face the big cube will look differently with different solutions. I could solve this puzzle within 45 minutes to an hour which I believe is not that good, however, nearly all small cubes have faces that go together with another random cube and you only recognize in the last minute that you have chosen the wrong configuration to assemble the big cube and have to re-start. This happened a few times to me but finally I do not think it is a very difficult puzzle and rate it a 5 out of 10. Everyone should be able to solve it with a little patience.
Consequently I can recommend this puzzle to everyone no matter if beginner, collector or crack. Only problem will be that it is no longer available and you will have to have a look at auction sides, Ebay or puzzle parties for it. I should also warn you that it can easily happen that a peg will hide itself in its hole due to using too much force trying to stick cubes together (which do not exactly fit) so please be careful.