Whenever I sow seed directly into the garden bed, due to the bizarre laws of physics, I end up with patches of no seedlings and patches where they are growing on top of each other.
I scatter seed by hand whenever the seed is impossibly small to be picking out individual seeds for planting e.g. lettuce.
Is there a technique I can use that results in a more even distribution?
I understand there is a tool available, but I'd prefer not to have one of every tool if I can do it myself.
You can glue seeds to paper napkins. Sounds weird, but I tried it last year with carrots and lettuce with mostly ok results.
I'm going to retry this year with toilet paper so I can have a nice, straight, long row of carrots.
It's somewhat time consuming to prepare the mats, but you get perfect spacing, and you can do it at night when there's no possibility for doing other garden chores. It also makes the outside part of planting time go very fast, which is critical for me because it's stressful to try to carefully space tiny seeds when the black flies and/or mosquitoes are sucking your blood. And it saves time on thinning, since the spacing is already correct.
Something I learned from my father for spreading tiny seeds like lettuce...
The best thing is, you can practice this technique in a controlled place (like over a piece of paper on your kitchen table) to be sure you're doing it right, then gather up the seeds and do it again for real in your garden.
I find that this technique works even better for me than using the seed sower I use for larger seeds (like spinach):
Another technique for spreading evenly small seeds is mixing them beforehand with sand.
After the mix, you will have more material that can be easily spread either by hand or by the technique proposed by Niall C.
Furthermore, the sand generally has different colour than soil, so you will easily see how even the sowing is.
Especially for round seeds, I take a pinch between my thumb and finger, and then kind of roll my fingers back and forth so that one or two seeds fall out a time. Do this while moving your arm along the row and you should end up with well spaced seeds.
Also, don't be afraid to pick them up and move them if you get a clump of seeds all next to each other in the row. Don't pull the soil over them until you like how they're laying.
