Lifetime Supply of Alum blocks -5$
The title can be somewhat misleading but I figured I'd link this as I recently spent 9$ on a 75g Osma alum block, and figured you could make quite a bit more for fraction the price by going for a little drive. In my case the Bulk Zone in my town had Alum powder for like 4$ a pound... might have been cheaper can't recall lol. But anyways I seen this link on youtube and after checking it out figured I should link it up here and save some of you DIY guys money :P.
How to Grow Large Alum Crystals by Crystallization - YouTube
Now their's a few more videos like this to check out if you wish to compare. Just type in "grow your own alum crystal".
I also had a cool idea of mixing essential oil with the alum block during the mixing for extra benefits like maybe a Witch hazel alum block :P best of both worlds haha. But I'm unsure if the crystal would still form with the added ingredients as I've never made one. But heres to those who do :chapeau