I might want to do a sour mash, if it's easy. How's it done?
Make a mash with the base grains and hold the temp at 100F-110F for 1-3 days. Preferably you want to cover the top of the mash with some plastic wrap as the Lactobacillus prefers oxygen free environments. Inevitably there will be some permeation of O2 into the top of the mash, that will promote the growth of pedio and some others and it will smell horrible. You can scoop the first inch or two out to not add that to the beer.
Some people mash a small portion till its really sour, then add it to a larger mash at brew day. Its a personal preference thing and there are a couple ways to get there.