Hello! I've made a few raised planter beds that are self-watering, so this is nothing new for me. What WAS new was that I painted it ... And at first, hated the color. But let me cover the assembly first before we talk about the paint.
I am bad. I don't measure things the traditional way. I go to my pile of scraps and bits, and see what I've got, and what's "close enough" that I can trim off minimally. That being said, I had four partial pallet supports (the parts with the arch for the forklift tines) that were approximately the same length, so that I'd end up with about a 34 x 24" planter box. It's built entirely from pallet wood, but with it painted, it's hard to tell. I wanted it to be approximately 36" tall, because when the box is assembled, I'll line it with a heavy-duty plastic liner, then fill a portion (approx 20") with gravel, then a drain pipe, a filler pipe, then put a water-permeable barrier (such as burlap or weed block material) to keep the soil from settling into the gravel (which is the water reservoir). The important thing to note if you build one of these is that according to the various sites I used as inspiration, you cannot have more than approx. 18" of soil, because water typically only wicks up about that much. At a deeper depth, the seedlings may dry up unless watered from the top. I used a mix of compost, soil, and manure, and checked my dirt depth. The drain pipe was nothing more than a leftover piece of PVC that I capped off on one end, cut to be slightly wider than my planter, and then put a 90-deg. Elbow on the other end. I drilled numerous small holes in it, then inserted it to sit on top of the gravel, below the moisture barrier after drilling a small hole in the side just above the gravel line. I made a tiny slit in the plastic so that it fit tightly around the pipe, and then sealed it with a silicone sealant. This planter box is for a shady area, and I've got some succulents and sun-sensitive plant in it that are not edible, so I don't have to worry about any leaching of that small amount of silicone sealant. I know these reservoir planters work, as this is my fourth one, and the first three are all making veggies! This one was just for a barren area in my yard.
OK - so on to the paint. Well, I buy returned cans of paint, and one of the colors seemed to be a sort of pale pink/beige color - not my fave, but not horrible. Good enough for small wooden stuff around the yard, right? NOT! When it went on, it was like a flesh color! I was horrified! So, trying to avoid having to repaint the whole thing, because the paint was a high-quality brand and covered amazingly in ONE coat, I came up with an idea to attempt my first craft acrylic paint artwork. I have to give the most credit to watching Bob Ross the painter (He of the "Happy Little Trees and Clouds" fame) as a kid growing up. I'd never tried painting, other than just my house, but I gave it a shot, and it came out better than I thought. It's not great - I know I'm no artist, but it's still a darn sight better than something that looks like skin!
So I'm posting this because I want to encourage everyone to give it a try - whether it be that first woodcraft project, or turning a mistake into a "Happy Little Accident" (ah, how I loved watching you, Bob Ross!) and have fun!