In the past I have tried just about all the seed sower helpers for trays to ensure accurate placement. I know various other ideas help for small seeds which violas are. Combining with sand for example, but none apart from one that uses your own breath to hold onto a seed stuck to a device, and then your breath is released and the seed is placed 100% in the desired position.
However that method takes for ages.
This is the best yet.
I do not know what the metal tray was for originally, but have had it for years.
I have cut down the number of holes with gupta tape and the sower fits a half tray filled with compost exactly.
The seed is placed on the plate then one finger moves each seed to a hole and places it in and gently pushes down.
I then sieve vermiculite on top and then remove plate and job done.
Getting good germination. Third attachment refers and only a week after sowing.
The seed used was radish about five times larger than some viola seed but for demo purposes ok .