- My client is selling glasses.
- Glasses need prescriptions.
- Prescriptions require about 10 Custom Options.
- Each Custom Option can have up to 360 values.
- That makes for about 1000 values in each product's set of 10 Custom Options.

So: 1000 products x 1000 Custom Option values = 1,000,000 database entries. For starters!

- Can one make a separate Prescription 'Product'

... that is part of the purchase 'chain', so that it's stuck in the customer's face, at some point in the purchase

... rather than a Related Product, (which they may not think to 'buy' AND which they CAN'T just tick and select, as there are further options to select in a spectacle prescription)?

Otherwise, I fear we will have a fat, slow, database.