I recently moved into a guest room that has uneven floors. There is a one degree slant over the entire room and some of the tiles are higher and lower than others. I'd like to set up a 6x4 platform over a portion of this room where I do work at my desk, and have just that platform leveled somehow. Other than just setting up some plywood, how would I go about leveling this platform in a simple way suitable for a few months (before we hire a contractor to fix the floors/foundation)?
This is small enough that you can simply build a deck out of 2x4 with a 1/2" plywood top (or thicker, depending on flex tolerance). You're essentially building a typical interior wall structure, but smaller.
Lay out a simple rectangle with joists at 16" centers (across the short dimension). Fasten it together with 16d nails or 3" gold construction screws. Slightly shorter fasteners could be used for the plywood.
Using a 6' level (or a shorter level with a straightedge extension), find the difference from the highest point to the other three corners, and cut legs or simple spacer blocks to level up the platform.
Large felt pads under each corner would make it quieter as you step up and move around.