This puzzle is Rikishi (Lixy) Ramada's IPP36 Exchange Puzzle. It is made from precision laser cut acrylic for both the tray and pieces and fits nicely into a standard CD case as part of the packaging. The details, text, numerals etc and instructions are beautifully etched onto the top and inside surfaces of the tray. A very high quality piece indeed.
The object of the puzzle is to cover up the tray with all the 6 given pieces but leaving a single date open. Since there are 31 days in August, there are 31 challenges here. What is interesting is also that each of the 6 pieces is a pentomino (ie shape made up of 5 square units) selected from the total of 12 possible flat pentomino configurations.
The design and shape of the tray provides 155 ways to pack the 6 pieces into the box, but for each date to be left uncovered, this will vary from date to date. The easiest challenge is the date 26th August, which has 22 solutions while 7 dates in the calendar have a unique solution. And of course the rest of the dates in between have varying number of solutions (see photo). Quite amazing how Lixy managed to find a combination of 6 pentomino pieces which can reveal any one of the 31 dates in the tray! Lixy had probably also chosen the month of August for his puzzle to coincide with IPP36 which officially ran from 5th to 7th August 2016.
I tried 26th August and it was pretty easy (given there are 22 possibilities) and next I tried my own birthday (9th August). 9th August has 5 solutions and this took me a bit longer to find. When it came to the dates with only 1 solution, well, you can guess....
8 August is not only interesting and fun as a packing puzzle (with not too many pieces), but there are varying levels of challenges inherently built in which can test the novice and the expert alike and anyone else in between. And If you ignore the year and the days and just focused on the dates, this puzzle can actually be turned into a perpetual calendar.