Just in time for spring, make pots for starting plants in out of newspaper, with no adhesive or tape. You can directly bury these in the ground which does not disturb the roots, allowing you to start delicate-rooted plants like melons and cucumbers inside.
The main cylinder is almost entirely hollow to save filament, mine uses about 8m of 3mm filament at 30% fill, which is very very strong.

The STL file is for making 2" diameter pots. The SCAD file will allow you to change the size.
Cut strips of newspaper the long way, about 4" wide. Roll them around the cylinder leaving 1.5" or so hanging past the flat end. Do not roll tight, leave it a little loose or you won't be able to get the cylinder out at the end(turning the cylinder backwards while holding the paper loosely can help). Fold over and press firmly into the bottom part, press really hard and twist a bit. Hold the bottom part and the paper while twisting and pulling the cylinder. Once the cylinder is out, the paper will lift right out of the bottom part.
Fill with dirt, insert seed. Put into a tray with a corrugated bottom and pour in an inch or so of water. Add water daily, enough to keep the paper damp.
When it's planting time, just bury the whole thing as suggested for the type of plant.
A note on the design - there is a hole in the top of the unit, but it's 0.01mm - it doesn't produce an actual hole but if it's not there, the inner hollow spot is fully enclosed and Slic3r/Skeinforge will print it solid, wasting a ton of plastic. By putting the tiny hole at the top, the object prints hollow.