Consideration if you're going to make ..
David Weaver
..your own. Most of these blinds have basswood slats or something very light, as the blinds will get heavy really quickly if you use something else
I don't know what they do to stabilize the slats, but if you're going to attempt to make these blinds, you'd probably want to have good power tools and a decent drum sander at the very least so that the slats are neatly done.
If you have that, the next order of business is making some test slats and letting them sit around for a few months hanging in strings to see how much they move around. When I was thinking about making some of my own (which turns out to be no cheaper than just ordering from blind sites who have mostly switched to having custom sized blinds made in mexico), I read post after post from folks who had used kiln dried wood, made blinds and then found that their slats moved seasonally in really unflattering ways (twisting).
I wouldn't be surprised if the slats on commercial blinds were heat pressed to really knock all of the life out of them.
The process reminds me of my first attempts at getting beech for planes. I finally found perfectly quartersawn wood that wasn't quite sawn perfectly pith on center. For about two years, the 8/4 stock that I'd purchased twisted and some split. Same thing with guitar necks - my second guitar neck was sawn by me out of a huge slab, as perfectly straight as I could make it. It still twisted a little, and since I only waited two weeks to see what it did, it slowly twisted after it was attached to a guitar.