I built an insulated box to store paint and varnish to extend its life and started with 100 watt light bulb as a heat source. I have a thermocouple inside that turns on light when temp goes below 80 degrees and off at 100. I put a cheap dial thermometer on the side so I could monitor the temp...
I have one from Lowes that I love. No problems since I bought it about a year ago. Got it on sale for $99.99. Appears they have gone up a little. https://www.lowes.com/pd/Kobalt-Auto-Darkening-Variable-Shade-Hydrographic-Welding-Helmet/1000003026
I tend to believe shops and storage building follow Boyles Law of Gases. No matter the size of the container, the gas (your stuff), expands to fill it.
Most projects I tackle are small or either repairs to something. I find that the first few welds look like my 10 yr old grandson did them, but by the end I'm thinking, dang I'm pretty good at this.