The life of a tomato cage is a tragic one. They start out all promise of giving your plants something to climb on, lean against and sometimes, they just don't work. One season later they are too rusty to make an appearance in your pristine garden, or they are forgotten in the yard where your daughter finds one with the new mower. (Don't ask.) You can find many of these rusted out treasures for free and some gardeners will give them to you so they can use new ones.
The secret to successful prepping for the poor is in repurposing old stuff for new stuff. Wrap the outer frame of the cage with either some vinyl netting or some chicken wire. Use metal clips to hold the wire or netting to the cage. Block the narrow end with netting secured firmly to the four "Legs" of the cage.
Create a funnel shape with a narrow hole about three inches in diameter and a wide hole that is the same diameter as the wide end of the cage. Secure the wide end of the funnel to the top of the cage so the narrow end goes into the cage. Your fish/crab/crawdad trap is ready for use. Place a bait box inside. A bait box can be a small can of cat food with six holes in the top of the can. The fish/crab/crawdads crawl in but they can't get out.
Tie a rope to both ends of the cage and drop it in your lake, river or pond and leave it over night. Return in the morning and see what's for dinner. Trade or barter your traps or your catch for something you want. All of this material can be used instead of new making the cost of these traps virtually free.