I need help with a simple step-by-step process to create a file for a rectangular tube that can be uploaded to get quotes for printing.
My idea is to: Step 1 create a solid rectangle with the outside dimensions in Tinker CAD, Step 2 create hole of the same length but with the inside dimensions, Step 3 align the hole to the centre of the solid rectangle, Step 4 group the solid and the hole, Step 5 save the file in the appropriate format, Step 6 upload to a selection of 3d printing services for quotes.
So far I have managed to do Step 1 and I think Step 6 should be straightforward. Therefore, I need simple instructions for Steps 2,3,4 and 5. They are probably there somewhere but I can't find them. Please help.