It’s an easy process. The advantage of alcohol tinctures over oil infusions is that you can continue to evaporate the alcohol if you want a stronger product. But obviously the alcohol is more expensive to start with. I use Spirytus which is 95% and available online or at shops like Gerry’s in Soho at around £37 a bottle. I know you can buy a litre of ethanol for half that price from Liquid Essences and I have bought from them before but the reviews have made me less sure that their stuff really is food grade. Even at £37 a 500ml bottle for the Spirytus by the time the mix is reduced to 100 mls you’re still getting a 1 ml dose for 37 pence so with the price of the weed included you’re looking at around £1.20 a dose if you start with 10 grams of herb.