Gregory has this to say about Tronc Commun: Tronc commun is based on the following idea: the two main pieces are common to the three puzzles: TC1, TC2 and TC3. I named those 2 main pieces tronc commun (common core in English) The common core is surrunded by 3 different sets of pieces forming TC1, TC2 and TC3. The level of difficulty increases with the number. One is easier, and Three is very very difficult. Finding the exact move to assemble the first three pieces of TC3 pieces is more than complex and the puzzler must be exactly precise.
Construction of this puzzle is excellent with very close tolerances. Fit is excellent at moderate humidity.
42 copies made for sale, each signed and dated. This puzzle is shipped disassembled.