Hello Samuel,
Good luck on your efforts.
Based on experience, there are many ways to make seed balls.
The reason we make seed balls is to protect the seeds from the birds,
ants and other animals. You can mix in compost and/or straw if you like.
Some seeds that germinate very easily, such as daikon or arugula you can just scatter right before a rain in the spring or fall, they will sprout and reseed themselves - but seed balls or cubes or whatever shape you come up with allow you have tens of seeds in one ball, and nature will choose what it would like to grow at that spot.
Your challenge is to identify the fruits and vegetables that your
land would like to grow naturally, and just offer these seeds to the soil. Every piece of land on earth has its favorites that will grow there, like weeds - no need for human input.
To make seed pellets, I have used ice cube trays as forms, door mats that have round openings, trays used by fast food stores to hold bread buns (they have small square holes) - once you start looking at stores and around you, you will be amazed how items can be used as forms for the clay.
Mix the clay with the seeds and additives, make the mix a bit wet, and use a trowel to spread the mix on the forms. This is usually done in the summer time, and the clay begins to dry up in an hour or two. Shake the clay of the form and let dry for a day. Store the pellets in a dry place and scatter when the time come. If you a lot of seed balls you may want to invest in a
concrete mixer, but for 1,000 square meters you do not.
Good luck - update us when you can
I hope this helps.
Kostas