Mouse Trap Poison Lock

I live in the country in the middle of cornfields so mice are always a problem. It’s easy enough to set traps but what do you do if they are in the subfloor, ceiling, or walls chewing up your insulation? I came up with an easy access replaceable poison setup that works really well and keeps them from running off with the block. If a poison block is not secured they will play with it and sometimes not eat it.