This print allows me to recycle 3D printing materials into a stick for a 3D pen.
I 3D-print the hollow stick, fill it with waste material, and put it into a hot glue gun. I then use the hot glue gun as a cheap 3D pen. I have used it quite successfully with PLA, but all the other plastics I have tried failed to melt enough to flow smoothly. Polyethylene terephthalate PETE (1), High-density Polyethylene HDPE (2), Polystyrene PS (6) have all failed and jammed the hot glue gun.
This simple design lets me recycle scrap materials which would normally be wasted; Supports, brims, rafts, misprints, etc. These can all be cut up and dropped into the stick (I tap them down with a bit of wire). I then cap off the end of the stick with the 3D pen, so that the material can't fall out, but leave a small hole so hot air can still escape. A printed stick uses 9 grams of filament, and a filled stick weights one about 15-18 grams. It is not a very efficient way to recycle material, but I find it is better than nothing.
Cheap little hot glue guns are only about 4W and don't have enough power to melt the filament. I use a "Bosch PKP18E" hot glue gun, which is 16W and easily melts the 11mm diameter recycler sticks of PLA. It cost me about $45.
I print the sticks successfully in PLA with layer height of 0.05mm, Walls of 0.8mm, 0% infill. I print them with a 30 line brim at 200 degrees on a 60 degree bed. The 11mm diameter and 30cm high stick takes a bit less than 10 hours and uses 9g of filament. You can scale the height or diameter in your slicer depending on the height of your 3d printer and the diameter of your hot glue gun.
To make sure the stick is open at the end, you can stop the print near the top. You can also let it print and then just cut off the top. Or you can, as I do, edit the gcode to remove the top few layers. I use cura which labels each layer like this ";LAYER:5980", so I open the gcode file in a text editor and search backwards for ";LAYER:". I then delete the last few layers so they do not print.
I have found the hot glue gun with the recycler to be a nice tool for drawing in 3 dimensions. I have made some test pieces, using both stencils and freehand. I have also used it to make some basic terrain for roleplaying miniatures.