Compost Worm Bins
It’s always better to have a compost worm bin that’s a bit too large for your current needs than a bit too small. The bigger the bin is, the better it keeps at the correct moisture level and the less often you need to empty it.
There’s no need to ensure that the joints of the bin are 100% tight and worm-proof. As long as you maintain good conditions in the bin, the red wiggler worms would much prefer to stay in the moist, food-filled inside than to venture out. I also don’t use a tight-fitting lid — I usually just lay a piece of cardboard over the top of the compost worm bedding to keep moisture in and light out. I’ve never had a problem with compost worms escaping from a setup like this.
It’s practically impossible to completely worm-proof a container, anyway. Even plastic containers with snap-on lids have enough gap around the lid for the worms to escape. All but the largest red wiggler compost worms can even squeeze through standard window screen. It’s far better to concentrate on creating good living conditions for your red wigglers than to try to create a “cage” they can’t escape from.