After almost a week of intense puzzling in the evening hours I finally could solve a really diabolic puzzle called EQUAL7. It was invented by Dr. Vladimir Krasnoukhov and entered the IPP competition in 2011. This little "bastard" is still widely available on Ebay, Amazon and other internet shops for under 10 Euros.
The puzzle is a cube shaped transparent plastic "cage" with 7 dices inside and one free slot in order to move the other dices around. Three fields are overpainted with a "5", "3" and "1" so that you can hide one dice behind those fields. There are 4 challenges which come with the puzzle. The easiest goal is to achieve the number 10 (adding all the dice dots per side) on all 6 sides followed by 11 (middle), 12 (hard) and 7 = EQUAL7 (extremely hard). In order to better show your final result the outer cube has a standing foot. Funny enough the easiest goal took me almost as long as the hardest puzzle till now, the SANDWICH from Vaclav Obsivac. To achieve 11 on each side took only 1 hour, followed by approx. 2,5 hours for "12" and around 4 hours for EQUAL7. Puzzlemaster is rating this puzzle a 8 out of 10 in terms of difficulty but I can not agree! At least it has to get a 9 out of 10.
I am not really sure if I should recommend it to everyone due to its difficulty (or maybe it is only difficult for me) but at least serious puzzlers need to have one. I can assure you that it is an awesome feeling to EQUAL7.