This is good for the home hobbyist. If you experience good success and want to try more, I would invest in a professional soil block maker that can do multiples at a time.
See this site for some great advise and ideas on the soil block method. I am not affiliated with it. http://www.pottingblocks.com/ The gentleman who runs the site is very knowledgeable and helpful in returning emails. He also has supplies and square soil block makers at reasonable prices. I learned a lot from all of the content he shares.
Step 1: Parts and Tools
2" inside diameter PVC pipe
3/4" wood dowel
circle cutter for use in drill press only
3/4" forstner drill bit
hand saw - not shown
Polyurethane - water based or similar to seal
3/4" wood screws
3/4" thick wood scrap (I used Pine)
The drawing shows the idea of the soil blocker. You can start off a seedling in a 3/4" block then transplant to the the 2" block, then a larger block or pot. No shock to roots.
Step 2: Cut Out Disks
Step 3: Drill Holes
Step 4: Dry Fit and Assemble
Glue in 3/4" dowel to the handle disk
Cut the pvc pipe to 3.5" long.
Put top disk in flush with the top. Drive a screws into opposite sides to secure.
Seal with polyurethane (3-4 coats)
Put handle rod assembly into hole
Attach plunger disk flush with bottom of rod for a solid soil block. Secure disk to rod with a screw.
Or attach plunger disk 3/4" up from bottom of rod to make a soil block with 3/4" hole to accept a 3/4" soil block transplant.
Put some candle wax on the 2" plunger disk if tight to help smooth the stroke.
Step 5: Finished Assembly
Step 6: Soil Block Mix
1/2 cup lime. Mix ingredients together thoroughly.
2 buckets coarse sand or perlite
3 cups base fertilizer (equal part mix blood meal, colloidal phosphate, and greensand). Mix.
1 bucket garden soil
2 buckets well-decomposed compost. Mix ingredients together thoroughly.
* From The New Organic Grower, by Eliot Coleman
Or you can use any good organic potting soil. I found a bag of Master Nursury Gardener's Gold Organic potting mix and it works great. I did make my own blend as above too, but it was expensive and time consuming trying to locate greensand, colloidal phosphate (gave up - could not find), etc.
Add 1 part water to 3 parts soil mix. Mix to a soft putty or wet cement (not soupy). A soil block needs to have the soil packed tight. Rinse out blocker in bucket of water after each block is made. This will help release each new block made.
Remember that soil blocks can dry out faster than soil in flats or pots. Keep an eye on them. Good luck!