A soil block maker. This is a stand-up model for 2-1/2″ x 2-1/2″ blocks. With the proper potting mix, these guys let you start transplants without pots. Make the blocks and place them in trays. There are block makers for 3/4″, 1-1/2″, 2″ and 4″ square blocks as well. You can also form the larger blocks with an indent that lets you pot up the 3/4″ starters to a bigger block (although this step may not always work that well). Johnny’s Seed (US) carries a full line.