3D Pen

3D pens use a handheld 3D printer that largely functions similar to a hot glue gun. This has one end where a piece of filament is inserted, then a button is pressed to extrude the filament from the hot end.

These can be used either by inserting a short rod of filament into the end, or by connecting to a larger spool of filament instead.

Many makers use these for refining their standard 3D prints or for acting as a glue to attach multiple parts together. Others use them as the complete tool drawing in three dimensions free form.