If you can get the 3D file, then it would be better getting a mould made and making them from silicon or outsource the printing to someone with a better printer capable of doing rubber. Protolabs maybe?
Rather than worrying about the stretch of the flexible filament you could split the hood down the centre and bond the 2 halves together. This won't stress the material. It would also be easier to 3d print as you would have a flat surface where the joint is, so it would sit on the print bed better.
I have a pair of Campagnolo Syncro shifters, they are 8 speed but i want to use a 7 speed block. Do I need to change the insert to a 7 speed or will the limit screw on the rear mech prevent the 8th position?
Is the pull ratio the same on 7 & 8 speed Campag downtube shifters?
Do I need this part??