Achievement:
Can IPA be used for growing DMT crystals?

Answer: no

Data:
Solvent used: Isopropanol 99.9%
CAS: 67-63-0
Tried: slow evap and freezeing
Substance: About 1g yellowish DMT
IPA used: 100ml

Steps:
1. Mixed about 1g dmt with 100ml IPA. No indication for oversaturation.
2. Freezing the 100ml results in no crystals
3. Evapped to 50ml. No indication for oversaturation.
4. Freezing the 50ml results in no crystals.
5. Evapped to 25ml. No indication for oversaturation.
6. Freezing the 25ml results in no crystals.
7. Evaped all the solvent. The result is a white/yellow paste.

Most solvents will never give any DMT crystals. They just dissolve it way too well. Then if you think backwards it means that even 100 µl of IPA will hold a good load of DMT. So it means it cannot precipitate unless you remove ALL the solvent and so never any crystal time!

I think actually all solvents that are out there from the hardware store are too good to be used. Naphtha might be the only one (?)

Cheers

I suspect that to have any chance of crystallising DMT from IPA it would be necessary to dilute it with water down to 30-40% abv. Then you might stand a chance of success with freeze precipitation, especially if you can wait a few months for the solvent to evaporate, or preferably apply vacuum while it's still deep frozen. This was how (minus the vacuum) I got freeze separation using aqueous ethanol, at least. The solubility of DMT in room temperature azeotropic ethanol is absurdly high and I wouldn't expect IPA to behave much differently.

If you succeed in producing crystals from deep freezing of aqueous IPA, expect to have to move quickly since it's highly likely they'll redissolve with even a small increase in temperature; it's therefore prudent to have an ice/salt bath at your disposal when removing solvent from the precipitate, and a second precipitation vessel for returning the solvent to the freezer to see if a second crop might appear.

All this could be considered distinctly inconvenient, but it's still useful science.

An interesting rapid crystallization of DMT can be done by dissolving in Et2O and adding cold heptane to it while stirring fast.

This possibly will work same with IpOH. But this defeats the purpose of this experiment as you could of just crystallized with heptane...

With an alcoholic aqueous mixture, DMT tends to just oil out when the alcohol evaporates overtime too.

Yeah, it's hardly a practical way of obtaining DMT crystals - slow evaporation of aqueous alcohol at -22°C over the course of three months - especially when so many alternatives exist But it did happen, so if you did only have access to vodka and a freezer, with time on your hands, it would still be possible to crystallise DMT.
And you're also correct, the short-term precipitation of DMT from aqueous ethanol at -18°C was an oiling out, which rapidly redissolved on warming up even a little.