Used to use a spare kitchen blender of the wifes, it was basically dedicated to making chum. Instead of throwing all the waste/old bait over the side to the gulls, we used to save it in a bucket - old squid and mackerel mostly; freeze once we got home. Then when not fishing - too windy or something, would have a session making chum, having collected loads of large plastic milk bottles. Grind down all the waste bait, and any old bait from the freezer that had got freezer burn, add copious amounts of fish oil and coarse bran. The resulting mix was all put into the milk bottles, and with the cap secured popped inthe freezer again until needed.
It was pretty amazing how much waste bait you could accumulate over a winter fishing season, and it could really be a bonus bringer in the spring. Take one chum/milk bottle, pop the cap off, and stab a few slices into the main bottle, just to allow water in to defrost slowly. Cable tie to the top of the anchor, then start fishing. Especially good for species like Black Bream, as the fine material just slowly defrosts and finds its way into the tide behind the boat. The average 2 pint bottle would last about 3 hours, soon knew when it had run out, the hectic fishing slowed. Used the same system for Tope and Congers when fishing rough or open ground marks - to similar effect.
Just needs fine tuning to how many holes you cut in the bottles to control the rate they defrost at. For drifting for sharks, used a similar system with slightly bigger holes, but obviously just hung overthe transom, and kept a check on them frequently - it is suprising how little is actually needed to get a substantial trail going in the water. No need to look like an oil slick, just a gentle flow of small scentedparticles - mostly to attract Mackerel to the back of the boat - then the sharks just pick up on the Mackerel feeding.
Hope that helps
Cheers from sunny Africa