When I first moved into this house, my office was almost empty and painfully echoey. I decided to build a sound diffuser to break up the bare wall and take some of the edge off the room. I chose balsa because it was inexpensive, soft, and had good absorption properties.
I sketched the roughly four-foot-wide arrangement in Tinkercad. The design was shaped around the blocks I could source cheaply, with the pieces cut at angles to reduce waste. I cut the blocks on the bandsaw, then built the panel outward from the center, gluing everything with good old Titebond and clamping each section as I went. A simple frame of wooden planks on the back holds the screws and hanging wire, allowing the whole piece to hang from a single point.
My first plan was to stain the wood with the leather dyes I normally used, but the balsa simply drank them up. Instead, I burned the surface with a blowtorch, removed the loose char with a wire brush, and finished it with teak oil. The process produced the dark, uneven finish that now emphasizes the different depths across the panel.
The diffuser made a noticeable dent in the echo, although ultimately filling the workshop with more tools, crap, and half-finished projects did an even better job. The finish also left me with a more serious lesson: I left the oiling rag on my workbench and woke the next morning to an office full of smoke. I haven't made that mistake again. The diffuser has hung above my workbench ever since.