Dear rogeorge, it is a big difference in making a stupid flashlight powered from two AA cells, and stuff powered from mains or other similar stuff, that can easily cause the user a harm, or property damage.
So, if you like having fun, then have yourself fun, but do not sell your ideas to others, as the correctly engineered form.
Just too many times I've been put in a situation, where a company needed something (cheap was likely the priority over everything else) and hired the first clueless "duino eng-uh-neer" to do the job. I was then the one cleaning the mess after, redoing all once again.