So, I like dungeon tiles, but they're ludicrously expensive, difficult to make, and cardboard ones suck.
The solution? Perler beads!
These little things are easy to use, and all you need to do to put them together solidly is fuse them with an iron (make sure to cover them with ironing paper though). They're also pretty cheap! They sell them at the party supply store I work at for a around 3 dollars for 1000 of them.
And here is the end result! I only have 3 at the moment, but tomorrow I'm hoping to make 6 more so I can have a decent amount to use on the table. Not as fancy as other solutions, but they give off a nice pixelated vibe.