[PureOS] Building my own PureOS ISO image?

Hi pureos-project,

I'm trying to build a PureOS ISO image on my own system but can't seem to locate a script/repo/documentation, etc. I'm probably just missing something obvious. To clarify, I'm trying to build an ISO like:

https://www.pureos.net/download/

... rather than the OEM image. I'm guess Matthias is the person to specifically ask here? (Ping?)

Just to underline it really doesn't matter how ugly/manual the process is or that it could potentially be improved — everything always can be and I won't "judge" anyone on the status quo, especially for non-daily processes; I'd just like to build one myself.

Best wishes,