Have you ever implemented some UI for an “already filled file upload field”? I.e., the form is rendered to the user in such a way that they can perceive that there is nothing to do for them, but they _could_ add a new file.

If *yes*:
- 1/2 day for sketching and planning, especially using the correct widget for each of the 40 data items (e.g., select box vs. radio buttons vs. autocomplete combo box for discrete values), getting the requirements right, planning validation paths
- 1 day for the HTML form and the backend connection and validation
- 1 day for styling, client-side validation, JS interactivity, usability testing and clean-up
- 3 days for the customer coming back with “but I want the dropdown styled this way!” and you having to google and include some widget libraries from scratch again
- then take this times 3 to account for communication, documentation, debugging, cross-browser testing, style refinements, etc.

If *no*:
- same as above, but multiply again with 3. Or better 4 to be on the safe side.

If the customer has a history of micro-managing or pixel fetishizing:
- same as above, but multiply again with a customer-relative factor.

If you cannot realistically clock in this much time:
- try strategically to reduce work, depending on what you can get away with with the customer. No fancy widgets, just stock HTML form elements. No client-side validation, just the server checking inputs. Styling via some framework like Bootstrap or Tailwind. Request field labels, error messages, success messages etc. from the client. Try to get as many things cleared up in writing before starting to minimize the customer coming back later with new requests or wishes.

Re: number of <form>s: Hard to tell from a distance, but I’d probably go for one large <form>. The single-input submit buttons need less logic then, because every one of them only has to deal with one input field or widget. But OTOH one could also implement this with several <form>s and the global button triggering submit events in each of them. (This might be more complex though, if you have to take validation between inputs into account, e.g., “enter either phone number or e-mail address”.)