Those are great-I had one for years and never used it. I have recently but even still it's hard for me to get perfect strips (I have problems with both hands and one elbow) so I am planning to get the accuquilt thing-but I'll use my shape cutter too now that I've remembered I have it. How awesome that you found a solution using something you already had!
btw I get elbows with a regular ruler and cutter too. I resquare after about 2 or 3 cuts.