The legal side analogue hardware modeling plugins – looking for resources

This is no programing question, but a question that maybe some fellow plugin developers round here might have faced before:

Let’s assume I’ve come up with a very nice sounding plugin emulation of some piece of analogue audio hardware. The user interface could be describes as definitively inspired by the look of the original hardware, e.g. same colour scheme and arrangement of knobs but with a more flat design, completely different font, a product name resembling the original but with some changes in it… I guess you get the idea, think of e.g. the guitar amp simulations that come with Logic. I don’t mention the original hardware that inspired me to create this plugin anywhere and leave it up to the user to get that link.

This plugin should be distributed as a freebie giveaway thing in an online shop, the whole code is made open source.

From looking at other products like that as mentioned above, I get the feeling that doing so is legally quite safe, but I’m only about 99% sure. But my googling on that topic revealed nearly no useful result. Possibly a topic especially relevant for the audio plugin industry. So, does anyone round here has some information on that topic, any personal experience, any blog post from some lawyer on that or anything like that?

I’m totally aware that I can’t expect real legal advice here, but maybe someone has some good hints for me :wink: