Not to be rude, but I’ll just say it plainly. This design isn’t anything new, in any shape or form. I’d just find an existing unit that fits your specs exactly. It will be much much (much) cheaper than building a functioning prototype from scratch, guaranteed. That is kind of the idea of Industrial Design in the first place… the create products for people which are more affordable (and require less time) than if they were to develop and produce them themselves as one-offs. More or less anyway.