I use something similar to that...with crumbles in one, pellets in another.
I made it using a 5 gallon bucket and drilled out holes on the sides at the bottom. Fairly big holes for the pellets (maybe not quite golf ball size) and much smaller ones for the crumbles. (more oval shaped and just slightly wider then a large drill bit, and a little taller than two drill bit holes). On the crumble bucket, I attached a planter base... a heavier plastic one, that potted plants set in to catch water. The lip on it is more shallow and bowls out a bit...maybe only 1.5 inches deep or so. Drilled a hole in the center of the buckets and planter base and attached with screw and nut. Bucket has a lid, that I drilled a small hole in the top-- probably not so important for the pellets, but the crumbles flow better with the hole. For the pellet bucket, I used one of those metal feed pans I picked up at
TSC. It's got much taller sides.
Both bases have about a 2" gap/space between the bucket and the sides of the base. On the deeper pellet bucket base, they cannot get in it to scratch anything out, but can eat out of it just fine! On the crumbles bucket, they sometimes can scratch at the base, but as the base empties, they have to peck at the smaller holes for the crumbles to come out. There's not much waste with either feeder.
I think the buckets with lids cost me $2. The base(s) were a bit more... both about $8. I had the extra bolts and nuts to attach them together.