Some technical ideas
If you want to personalize with few resources - try making your own paint. I recommend you use non-toxic pigment (and still use masks - just to spread awareness), and there are a bunch of non-toxic to fairly harmless liquids to mix stuff into (e.g linseed oil*). You can get a lot done with mortar and pestle for personalization scale.
Other things that help are fabrics with nice haptic properties (you can sew together patch-work style). Needle skills are nice to have anyway if you want/have to live low budget. Just make sure you get good thread. Fabric will also improve overall acoustics.
Pull broken head-phones out of the trash and fix them (9/10 are broken at the jack, you can fix them with almost nothing, if you are good you can re-use the solder that is already on them. Then you only need a lighter/candle and e.g. some liquid adhesive and string to fix things permanently. A quiet atmosphere and my (home) sounds around me help my mood a lot.
LEDs are another option for color personalization instead of paint. If you DIY, just make sure you understand what resistor you need. You will need one unless you do plug in LED-bands which are relatively expensive (but still not bad, you could also cannibalize them). If treated right LEDs will last forever though.
*Not sure how well that works on particle board though. Epoxy is the solution that will always work (and can also be used to fix a lot of other stuff) but is potentially somewhat toxic, moderately expensive (if you buy a big just past shelf life bucket), and needs some know-how and tools to avoid a utter uncleanable mess. Hit me if you want more details.