Admittedly, this has limited use outside of the cruise boat industry, but hey, it’s an idea and it is feasible.
Currently to board a cruise ship, you present your ship card (looks like a credit card), to a security member who scans it and waits for confirmation as to who you are. Add a simple scale to where the person being checked stands and get a baseline weight. This can be done with no user involvement, no embarrassment that anyone will know a weight is being taken. In addition ot the scale, mount a simple scanner for getting a height reading. So far you have about $100 dollars in parts per entry.
The weight and height will give you a rough BMI on the person, allowing you to calculate an estimated alcohol uptake scale.
Now, whenever a person orders an alcoholic drink, they must present their card and it is scanned by the bartender and the drink is then served after being billed.
A robotic bartender (Actually just a pouring unit, which there are many out there now), can get your alcohol uptake scale (estimate) and dispense the first drink normally.
Savings come into play with each additional drink, to maintain the alcohol level in the blood stream, it takes progressively less and less actual alcohol over the number of drinks served. The robotic bartender can ‘water down’ each successive drink with no loss of buzz from the customer.
Run with it guys!