I'm dabbling in growing microgreens for a local restaurant, Magnolia Thomas. They are a delicious addition to salads, soups, appetizers, sandwiches, the list is endless. I went ahead and bought some non-GMO, 100% natural seeds and made a reusable shaker for the smaller ones. Celery seeds look like sawdust, a puff of air and they're everywhere. If you put the desired amount of seeds in a ziploc bag then open the bag around the mouth of a glass jar with little holes in the lid you can season your soil to your liking and then cover with dirt to the appropriate planting depth. Voila! Makes handling these tiny seeds much easier and you can reuse that one "seasoning" jar for all the other small seeds. Pictured below are the tools used to make my jar. I found it very easy to nail holes into the lid using a piece of sturdy styrofoam as a surface, it was left over from a packaged TV. Made it super easy. One good whack and you have a small but effective hole.
So today I planted Utah Celery, Detroit Dark Red Beet, and Arugula seeds in 11 x 22 x 2 trays using the seed shaker. For the medium, I used a third of each mushroom compost-peat moss-garden soil. I then played around with ideas to form a microgreens shelf using metal dowels to hold up the long sides of the seed trays. Still not sure about that design, its a work in progress.