Binding tool for sewing 4cm

Print it standing on one of the open ends. No supports needed, but a brim is recommended. When using the tool, cut a 4 cm wide strip of fabric with a narrower tip. Feed it in from the flatter side and feed it through with the tip of your scissors, and pull from the other end. The strip should get folded. Pull the folded fabric back a little and start ironing while the tool is pulled forward. Now you have a strip of fabric - folded over on each edge.