We’re trying out newspaper pots for this stage. They were a bit tricky to make, though I got the hang of it after about 20 of them. Essentially, you wrap a strip of double thick newspaper around a jar or can, folding down the bottom as you go. When you get to the end you try to tuck the last corner in under somewhere, pull the jar out, and fold the top edge down to secure everything. That didn’t always work. I suppose you could just glue them instead. They are quite sturdy so far, though the planting room smells vaguely of wet newspaper.
The downfalls of newspaper pots that I foresee are that they can’t be sterilized before reuse and that the newspaper can’t be recycled if it’s too dirty. We’ll be able to compost the pots when they run out of life, so it’s good use of existing material for us (we get weekly newsprint fliers in the mail). On the upside, you can make them when you need them instead of storing plastic pots (or if you run out of pots halfway through planting) and they are free if you have a source of newspaper.