Granola bar making?

I’m not sure what you mean by “professionally”, but for most of them you don’t even need anything like a blender. For the most part, all you need are whatever ingredients you want to use, and a baking pan and/or cookie sheet.

Recipe

No blender required.

I think it depends on how large of an operation you would like to have (what I mean is, how much do you want to sell). If you are doing relatively small scale, like to sell at farmers’ markets, probably a few trays of bars is more than enough.

You probably want to experiment first with different recipes. You also need to think about packaging. Cellophane wrappers, labels, stuff like that are all things you’re going to be thinking about. Also, are there cottage laws in your state where you need special permits in order to sell food that’s been made in your home?

It’s going to be nigh on impossible for someone to advise you without having some idea of the scope of the operation you have in mind (professionally?) and the laws in your area.

Your best bet is probably to find someone in your area that is selling something similar to what you have in mind on about the same scale you have in mind, and pick their brain.

It can be informal. If you’re thinking about selling at farmer’s markets, for example, vist the markets in your area and ask the other food vendors simple questions. “That’s delicious! How did you ever get started selling them!?” A little footwork and a little flattery will get you there more quickly than we can, here.

Good luck!

Not sure about professionally. But sometimes I use a grinder on things like flax that I might put in them.