You could use a stil a bunsen burner and what you'd do is vaporize off everything with a boiling point below the boiling point of thc then vaporize at the boiling point of thc to get pure thc extracted through the stil. Its probably not that hard if you can control the temp enough
Edit: correct spelling is 'still'. The process is the same as distilling water except different temps. And just remember that if you don't distill off everything with a lower boiling point than thc you WILL get other cannabinoids in your final product. You may also consider processing it a few times through, so anything with a slightly higher boiling point will get stuck in the tubing without making it to the final chamber for purity sake, however first process should get you in the range of 99% pure if you have a temp accuracy of +/- 0.1 deg f or so.
I want to do this in the future and try isolating a few different cannabinoids to use for different things. Anyone who has done this let me know I'm very interested