I used two of those red party cups:

Take one cup and drill holes in the bottom.
Take the other cup and cut out the bottom and cut along one side then place it inside the cup with holes.
Fill with potting soil, water slightly
Place seed, water slightly

Then when time to transplant you gently pull out the inner cup and place it in the new pot and slide the cup out and pack the soil around the seedling.

Make sense?