If you search above for suitable recommendations for free cad, and show your sketches with each part labeled either 1,2,3 etc or A,b,c etc then others may give some recommendations on how to nest i.e. take 'A' put it in the bottom left corner rotated so the top is at the bottom along the straight edge, 'B' placed above 'A' rotated anticlockwise against the left edge with 3 mm between A&b, etc, draw them in the cad see if they fit and show a sketch / screen shot etc, just to give an idea of how its going.
For instance, I have in the past being toying with creating a E class container ship (of a US navy sealift type) with the internals fully open, cutting a frame, there would be a lot of material wasted in the centre cut out, so the idea was to draw the frame 3 times to be sandwiched together, but each frame would be split into 4 parts that all cut out as strips, they create the frame and the next would sit on top but the joints would be in a different locations so that a joint is not on top of another e.g. 1st layer, long horizontal strips short vertical strips, 2nd layer short horizontal strips long vertical strips, 3rd layer the same as the first.