Update, I made a full box of shallow foundation using the pour and press method and installed it in on of my bigger, more active hives last week. Doesn't seem to have a flow going on right now but the Cabbage palms have started which I hope will stimulate the bees into drawing out the flat sheets of wax. I'm interested in seeing if the hive will reject or use the flat foundation. If this batch works I'll switch over to wiring the frames instead of using fishing line which has a lot of stretch.
Home made flat foundation might only be useful as starter strips. Only time will tell, you can't rush the bees into doing something they don't want to do.