But surely (Shirley) those are just small straight edge rulers you are holding against the foot ???!!!
OK, one is in the shape of a Dresden plate so you can use it as a template but Jeez Louise its just a straight edge!
I have a 6", a 6 1/2" sq ruler and a 12 1/" sq one all with 4 straight edges, and a 24 x 6 with 2 long straight edges,
not to mention the Binding Tool which doubles as a friendship braid template!
I thought Mali meant the one where your foot sits in a groove in the ruler ?? but then you still have to hold the ruler straight!
For long straight lines try masking tape!