What with the impending move* we couldn't afford to buy a seeder this year. We also intend to use ruth stout method mulching and that is not compatible with a push seeder. So I made this in about 20 minutes. It is the Hobbs Seeder version 1.0, is 4 ft long, and is simple to operate. You just jab the pointy end into the ground to the depth needed for what you are planting, lift it out, drop a seed into the funnel at the top, and tamp it with your foot. Repeat as needed. The materials needed are a dowel or broomstick, a length of half inch ID tubing (metal helps use less force to poke the ground), something like sheet metal or thin cardboard to make the funnel, and duct tape. Lots of complicated jab seeders exist and I have one for large seeds from the 1880s. This one though is dead simple and anyone can make it. I already had copper pipe for this but conduit would work too.
*(we are under contract for a farm near Portsmouth OH)
I use something similar, but without duct tape or the added poker stick. Just a pipe, cut off at a 45 degree angle. Depending on the size of the tube, it can plant anything from small seeds, potatoes, onion sets, even transplanting tomato starts.
The secret to not plugging the tube, is to put the tube on the ground long end facing away from body, and then use a foot as a fulcrum to press it forward into the ground. For harder ground, I prefer to use metallic pipe over plastic.