Yonaton Setbon (
on Instagram whose main knot related focus is lanyards (scoubidou, plastic lace sennits) has written a knot editing tool called
Open Strand Studio. It is written in Python, released as open source and available from SourceForge.
I have not tried it enough to see how focused it is on scoubidou knots or whether it could easily be used to draft generic knots.
