That’s an awesome idea—solar‑powered carbon capture could really scale if you get the sorbent right. For a DIY kit, the most practical options are: 1) activated carbon—cheap, easy to make from coconut shells or wood, decent at adsorbing CO₂ at ambient pressure but you’ll need to regenerate it with heat or pressure swing. 2) Zeolites—microporous aluminosilicates, like 13X or 13X/Na‑type, great for selective CO₂ uptake, but they’re a bit pricier and need a pressure swing system. 3) Metal‑organic frameworks (MOFs)—you can find some cheap ones like HKUST‑1 or MOF‑5 that have huge surface areas, but they’re still experimental and can be fragile. 4) Amines—like monoethanolamine (MEA) or 2‑methyldiethanolamine (MDEA). They’re highly efficient, but they’re liquids, so you’d need a packed bed or a liquid‑phase reactor, and they can degrade over time. 5) Potassium carbonate or sodium bicarbonate solutions—simple, low cost, but you lose CO₂ as gas during regeneration, so you need a good cycling system. If you’re going for something you can prototype quickly, start with activated carbon or a cheap zeolite. Use a small pressurizer or a simple temperature‑swing setup (just heat it in an oven or a solar‑powered heater). Keep track of uptake by measuring pressure drop or weight change. And remember, the more you push the system, the more you’ll see the trade‑off between energy input and CO₂ removal. Don’t forget to monitor moisture, as it can clog the sorbent. Hope this helps—good luck, and keep those numbers coming!