Good day all, I have been considering for some time building a Stirling engine but the difficulty has arisen what to use as the displacer piston. The plan suggests an aluminium cigar tube (not an option) so have been looking for a substitute. I have now found a suitable part, however it is rather larger - Ø27mm. than the plan calls for - Ø20mm. I have read that some designs of model engine do not re-scale well (or not at all). Would this apply to the Stirling engine or is it feasible to increase the size to accommodate the larger component? Thanks for your comments and advice. cheers John K.