Speed rant #2
On the topic of drug-induced creativity, I'd just like to give my 2¢ about that, as the reason i was initially drawn to drugs was because the guitarist in a band i really liked at the time said in an interview that acid was "like magic for the creative psyche", and having been a musician and artist since age 3, I wanted to get in on some of that!
IMO if your not a creative person, drugs won't change that. I believe there are two mind types, creative minds and practical minds, and you can't simply change that in a person. To say someone is "creative" doesn't necessarily mean that they have to be an artist in my mind, but rather that they thrive on imagining new alternate ideals or ideas to the ones that are instilled in us from birth, while the practical minds are geared towards survival and progress. That's my hippy-ass theory about the mind and creativity, and when you introduce drugs to the picture, creative people will often find that their creativity increases when on certain drugs, different drugs increasing creativity in different ways.
Having said that, drugs that will make it easier to get creative include stimulants, cannabis, and sometimes alcohol for me, so of those, the OTC drugs that would serve this purpose would be caffeine, nicotine or any kind of OTC stimulant.
As far as drugs that will inspire creativity, but won't necessarily make you immediately feel like getting creative, the way to go is hallucinogens. Unfortunately OTC hallucinogens kinda suck IMO, the only one even worth trying is DXM. If youre looking for drugs that are not sold over the counter at drugstores but are easily obtainable and legal or quasi-legal, san pedro cactus is by far the best option, and it grows everywhere in the southwestern part of the country, and is cheap and available for order on the interwebz.
But try to find your creativity on your own before using to drugs to induce or enhance it.