When I lived in London I did a short course in furniture design at Central St. Martin’s College, run by Ben Panayi. As part of that course I produced a design for a lampshade made from polypropylene.
I later simplified the cutting outline so that, while it looked the same when assembled, it now comprised of 4 identical shapes plus one other small shape in the centre. In what ended up being my first ever foray into digital fabrication, I asked Medway Cutters to use their craft cutter to cut this as a trial/prototype.
Craft cutters use a drag knife, which works as the name implies: a knife is dropped into the material, then dragged along the lines specified in your CAD file. Being a drag knife with an angled blade, it means that there will be a slight over-cut where two cutting lines meet. Being 1mm-thick polypropylene though, these were very minimal in my lampshade.
I have kept this lampshade since then and brought it out again recently to be part of the design for a new floor lamp:
It is something I will definitely continue with for this or other pieces.