When collecting wildflower seeds for prairie restoration, hundreds of seeds can be enclosed in a seed head, (think of sunflowers.) I needed a way to quickly and cheaply break down the heads to extract the seeds for broadcast planting. Sure I could pay someone to process the seed or I could buy the expensive equipment, but this seems to work well and cost me about $5. I picked up almost everything from curbside trash at spring cleanup. The $5 went to new fuel line to fix the junked weedeater and to some .25" hardware cloth.
This doesn't work well with hard seed heads like echinacea, penstemon, and rose hips. For those seeds I made a smaller version of this using a five gallon bucket and a blender motor. That thing really rips things apart well without damaging the actual seeds.
A round 30 gallon trash can, already had this, new $20 (Use a plastic can, this metal one cuts the line a lot where the screen is attached.)
Gas power string trimmer, free or $60 new.
Lawn mower handle, free from junked mower.
.25" hardware cloth.
Some scrap wood, 1x6 board, 1x2 and 2x2 pieces.
Curtain rods or plumbing strap.
Deck screws and some bolts.
A throttle adjustment lever from a mower.