More junk box engineering where the idea is more important than the execution...
If you've ever used a pellet air rifle/pistol you may know that handling and loading the pellets, especially in the field, can be frustrating. The pellets are small, must be correctly oriented, have a delicate "skirt" that must not be damaged, and are difficult to find if dropped. In the case of single shot, breech-loading rifles the scope blocks the breech from above making loading with big German fingers especially difficult.
One solution to this difficulty is the so-called pellet pen. Think of it as a hypodermic syringe that dispenses pellets instead of fluids. You load it while in a comfortable location and then use it to place a single pellet when reloading the rifle. It can slither under the scope and dispense a properly oriented (skirt to the rear) pellet much more easily than I can hand load.
I have a commercial 0.177 pellet pen that I use with my "bug buster" rifle and it makes things so much better that it sold me on the pellet pen idea.
I needed one for my 0.22 caliber Crosman 2240 pistol but the only commercial one I could find...
has some distressing reviews and, at $11.50 for what is little more than a plastic tube, is grossly overpriced.
I hunted through our huge collection of pens and pencils and found one with a body bore slightly larger than 0.22. Quick work with a miniature chop saw produced the blue tube shown in the photos. An artfully scissored scrap of soda can, tightly secured with painter's tape that matched the color of the tube (SWMBO says that's important) completes the syringe. The plunger is made from a bamboo chopstick (always grab some when eating Asian - they have hundreds of uses).
This closeup of the business end shows the two "fingers" made from soda can aluminum. They bend aside under pressure from the plunger to allow a pellet to discharge, then snap back into place to prevent the next pellet from emerging. Dead simple but effective.