Pretty new to Blender here and with a pretty specific set of questions.
The situation: I'm a vet looking to operate on a dog's spine. I want to put screws in a very specific location to avoid damaging the spinal cord (the corridor is about 4mm in diameter - I'm going to use 2.7mm screws with a 2mm hole drilled at exactly the right angle).
My strategy: I have a CT of the spine that I have extracted into CT slicer, exported as an .stl file and made a 3D printed model of. I am planning to 3D print guides on the left and right side of the spine that are shaped to snugly fit the spine with holes already placed to guide drilling before the screws are placed. I have imported the .stl of the spine into blender.
My plan (halfway through completion):
- Make a new cube (several thereof), size and rotate for the approximate angle, place over the appropriate region of the spine
- Add a Boolean (difference) modifier to the cube with the spine as the target
- Slice the (now shaped) cube in half to give a left and right side that can be placed on the spine in surgery to fit
- Make a new cylinder the right diameter and length for the drill guide. Rotate and place into each guide, add a Boolean (difference) modifier to each guide with the cylinder as a target
- With a complicated 3D shape such as a spine, I need to carve the guides appropriately so that they can be slotted into place onto the spine from either side.
- I have been doing my carving with Boolean modifiers applied to each guide and extra cubes as needed for targets to shave off appropriate areas
- Sometimes the carving leaves the external mesh of the guides intact, sometimes it doesn't and I have to make new faces where old ones have been removed (not very straightforward but achievable by tabbing into edit mode, selecting edge loops via multiple vertex selection, using the C button to highlight select vertices then F to make faces where necessary)
- Overall I'm getting there but this is an incredibly slow process given that I still need to print the shapes and test them for fit on my printed spine before going into surgery.
Surely there is a quicker way to do this? I tried placing each guide on the spine and moving it along the X axis in incremental stages towards the middle (where it is supposed to be), applying Boolean modifiers along the way, but this invariably disrupts the mesh and leaves me with a million faces to recreate (and not confident I'm recreating them in the right places).