Fons and Porter rulers. Waste of money as there are much easier rulers to use.
Bobbin winder that makes a mess.
Specialty rulers like the xblock which I have never used since I lost interest before I got around to use them.
June Taylor shape cutter ruler, just not worth it and its just as easy to use a regular ruler and no folding the fabric to fit the ruler.
I love may rotary cutting mat and use it alot and if you twist the rotary cutter blade sharpener back and forth alot with a little pressure they do work.