I loved the proportions of Qjr's no. 4 scalpel handle, but the part was a little loose. I remixed it to be stronger near the blade, lighter in the handle, fit the blade tighter, and have rounded sides. This file prints perfect for me and the blades audibly snap in. Surprisingly durable and flexible in PETG.
I printed these at 100% infill, 0.1mm layer, 0.4mm nozzle. The trusswork is 0.5mm wall.
Please note, these are not sterile and can break. Be careful not to cut yourself when installing/using/replacing.
Also available: Scalpel Truss Handle - Size 3