Hang a small piece of (uncooked) meat (bologna) inside a gallon jug. fill the jug 1/3 full of bran. Cut a hole near the top of the jug and cover with 1/2x1/2 screen so the flies can get in to lay eggs. As the maggots grow, they fall off the meat and are cleaned by the bran. You can increase the size of your operation as you see fit.
put some corn meal in the jar, then place the jar in the freezer for three weeks. After three weeks take the maggots out of the freezer the maggots will be huge! Fish the maggots using a #4 gold hook with no bobber. Let the bait fall to the bottom slowly and wait for the fun! It won’t take long. Maggots are one of the best crappie and bluegill live baits I have ever used but I don’t use them much because of obvious reasons.