This is our vacuum seeder. It is a simple device that works. Here we are sowing pelleted seed of lettuce. The vacuum hold the seeds in place at each hole. The holes match up with cells in the tray of compost. Once the excess seed is removed the tray is tipped over the tray and the vacuum released.
I like simple and elegant solutions like this.
We have extra trays that hold broccoli seed others that work on basil but it sows too many doubles of tomatoes and peppers. It has saved enough time to pay for it self many times over. Being efficient is important as we always have to improve productivity to keep ahead of our ever increasing costs.