I am a final year product design student and desperately need advice on how the internal technical aspects of my product will work! It is a skincare (face only) dispenser with 5 individual 100 ml tubes that house the liquids. It will sit on a surface in the bathroom environment. I imagine each tube will need a pump and motor to push a pre-determined volume of the liquid out of the nozzle into the users hand. The user will be able to select the product they require and when they put their hand under the automatic sensor, the product they have selected will be dispensed once into their hand. I hope this makes sense. I am not an engineer/mechanics/electronics student so I really am just trying to understand the basics or if anyone could offer some advice/direction I could take that would be amazing.