Potting mix steamer

When i did my horticulture course 10 years ago they had a big machine that produced and pumped steam through perforated pipes at the bottom of a small covered cart full of potting mix. It was used to pasteurise the medium to organically eliminate harmful organisms, pathogens, weed seeds and create an ideal environment for starting seeds, cuttings, and young plants.
I've looked back through my notes and it says "reach 80°c (180°F) for 30 minutes to sanitise old or new potting mix".
I'd like to replicate it as I'm also a qualified metal fabricator now (thanks to night school) but all I can find online is huge industrial ones for doing outdoor beds. Has anyone tried making a smaller version? I'm thinking even just being able to do 100lt at a time would be useful for starting cuttings, seeds and potting up. Maybe hook up a simple wall steamer? Or multiple if extra volume is needed?
I've seen wall steamer's used in conjunction with a steam box in woodworking for bending timber.

Here's a large one I found online for steam treating commercial quantities.

Mushroom growers use pasteurizers about that size. Lots of DIY examples on YouTube, or at least there used to be