there’s more than enough info on his site to try and recreate some of his experiments, but perhaps you should start here instead: How to Design, Build and Test Small Liquid-Fuel Rocket Engines.

Among the investors was André-Hubert Roussel, former CEO of ArianeGroup, who oversaw the development of Europe’s only ...

It’s an extremely impressive piece of kit, and hopefully [Rocket Moonlighting] will release the CAD source so we can make our own. EDIT: [RM] tells me his engine cost less than $2000 to make.