What I'm thinking of is a household version of the machines they use to grind down the old Christmas trees in January.
I do a fair but of composting but this works better when everything is pre-pulped. Like anyone I also accumulate lots of cardboard which isnt taken at the local recycling. I could compost a proportion of it (this is recommended to get the right balance in the compost) and pulp the rest of it for ease of storage and transport to nearest recycling centre that takes it, say, 3 times a year. I presume the same could work for plastics which again arent taken at the local recycling. It would be far easier to deal with a mound of finely cut plastic or cardboard in a barrel or box in a shed rather that bulky bags of the stuff.
Anyone ever heard of these such a "grinder" or know where they can be bought?