The thing about putting wood together like that is that it actually requires A LOT of tools to do well.

It's not just a matter of gluing them together. The won't withstand much force against the face of the wood if you simply just glue them together. If they warp over time, a weak joint will also cause the entire piece to crack. And don't underestimate warping, I've had random tables practically explode because one day the joints just gave out and the warping couldn't be stopped.

First, start with good aged wood. Fresh lumber with lots of moisture is bound to warp over time. You don't want to paint on something and then a year later, find the wood has curved slightly and your artwork no longer looks the same. Once wood has dried out and already warped, that's when you shape the wood into its final straight product.

What you're going to want to do is first you need to JOINT the wood. Not join, JOINT. You need a jointer for this. You can also use a planer but need to be a little more precise. You need completely FLAT and PARALLEL sides to join together (parallel and flat are not the same!). Any curvature or imperfection on the side-face of the wood will create a weak joint.

Some people would suggest using dowels. I've read a lot of opposing/supporting arguments for dowels but I prefer not to go down that road of even more specialized tooling for probably a tiny difference. You can also look into different methods of joinery. Essentially you're cutting shapes into the wood so it gives you more surface area to apply glue and stick together. This can be especially difficult without proper tools like chisels, measuring devices like measuring tapes/calipers.

You're going to need a lot of long, good quality clamps. To buy clamps long enough for a glue-up like this, you're looking at $30-40 PER CLAMP. I would guess you would need probably at least 3, safe bet would be 4.

Other random things you'll need include a heavy workbench you don't mind getting dirty/damaging. If you're using a hand planer to clean up edges, you need something HEAVY to clamp your piece down to or else trying to run a planer and shave off a layer of wood will just tip over your table. You also need a heavy table clamp which can easily be a $100 or so. Electric planer/jointer, electric saw, chisels, hammers, glue, measuring devices, etc. are some other random things you might need.

You're frankly better off buying this premade somewhere unless you really plan on doing this a bunch. This really isn't in the realm of simple DIY though unless you're okay with a more rugged outcome. If you want a very clean, very straight result, you need lots of expensive and precise tools. It seems like a super simple thing but just wait until you try and do it with minimal tools and you'll end up spending hours just to clean up the sides of the board, let alone any joinery work, glue up, sanding, and staining. Then you need a proper place to let something like this dry (not inside your home where the fumes of glue/wood stain will make you sick). If you don't have a garage, you better hope it doesn't rain or bugs don't fly on your freshly stained product.

In my experience, Home Depot sometimes keeps random pieces of "diy" wood in stock. It's generally pretty limited to home-building materials but you can find a few pieces of boards that look just like the ones in your picture (although they might be thinner which gives them a less "substantial" feeling) that are already glued together and a final product.

Not to discourage you from doing this because woodworking is tons of fun and there is so much room for creativity. But this isn't exactly an easy task and could require a decent chunk of starting money even for the simplest process.