Hi again OG56 and thanks for the recommendation of Fusion 360. I must give it a try. So far I have been trying out FreeCAD. Now, I do not have a 3d printer, so there's a lot I I don't know yet about the reality of getting models to actually print, but given that it strikes me that it's not so hard to create the CAD model, not hard but it is laborious. I say not so hard, however like all complex software I note that there's quite a few hours of work to get to even have a minimum proficiency. When I was a child, my father would design and build moulds for injected plastic parts in the evenings at home. I was aware from an early age of issues like shrinkage, and having to add tapers and to round corners to allow parts to release from the mould. Of course, 3d printing adds some new challenges, like overhangs, but does not perpetuate all the old ones, like the release issues I mentioned. The same basic idea that you have to think quite thoroughly about how you are going to make something before you even start is still there it seems.Thank you for the mention of PLA and TPU. I have to admit to being intrigued as to how well TPU would work for printing customised gaskets. Also just the sheer number of different materials it seems can be used with 3d printers.