I use that method, using interfacing cut to go through a printer although I suppose one could draw or trace the patterns but that would be a lot of work. I use a product by June Taylor called Perfect Piecing that i get at JoAnns or anywhere that carries something similar. What i like about it is I don't have to remove the interfacing once the block is finished like you do with paper. The one thing you have to remember is to make all the foundations the same size so the final product will turn out right. My printer also serves as a copier, so I just load it with the sheets & copy the number of sheets I need. I also use a ruler called Add a Quarter which has a lip to add the quarter inch seam allowance when you trim the pieces. Hope that helps.
Cathy S./ Willowwind