Want to modify a complex shaped plastic part; need a good, inexpensive, scan/service

[LambdaFF]

Ok, getting the outer shape is easy, you're making this way to hard on your self. Do the same steps as above, but when you take your photo, put a ruler in the pic, say a 20mm length.

Works too. Splines are cleaner. :-)

As mentioned. 30 minutes. .

Yep.