I just found this tutorial on using Blender for getting files ready for printing. It’s pretty good.
https://youtu.be/zHxs4uerHjw
Very good . Thank you .
https://youtu.be/ZnCf-5G7DYc Here’s another one but it has a flaw in that models should have their subsurf modifier applied prior to doing a boolean operation. Its pretty good apart from that.