DIY soldering stand.
Assuming that’s a temperature-controlled soldering station: make sure the tip isn’t in contact with the coil, or the iron will keep pumping heat into it to compensate for the thermal dissipation.
I have also made a step by step guide on DIY soldering flux a while back on hackaday. Also kind of a "broke a.f. edition".
https://hackaday.io/project/187703-rosin-soldering-flux-diy
I’ve made flux by dissolving rosin in isopropanol (at various concentrations, from just a few % solids, to thick and syrupy, probably around 50% solids, and concluded it’s not useful for most purposes. It’s just not active enough. I have used it as a protective lacquer for bare copper on PCBs to preserve solderability. But for serious use, like the more heavily oxidized parts that are what actually need extra flux, it’s just too weak.
I would also strongly advise that you not suggest this flux is healthier to use. Rosin is a known respiratory hazard. Sure, the activators in commercial rosin fluxes (never mind the stuff in newer no-clean and rosin-free fluxes) are quite bad and perhaps feel more aggressive, but rosin fumes are quite bad on their own, despite having a somewhat pleasant smell.