I need to create a 50 item check box, PDF, order form with an option for quantities

Could you please elaborate a bit more on what you are looking for? It seems that your question did not get submitted completed. You can add as many items in a check box that you require.

Yes, the box cut me off.
What I'm looking for is an order form that would allow for someone to
click on a box next to an item number that would be associated with our
catalog of items, and have a drop down dialog box to specify quantities.
It would also need to have an additional comments box. Since these
particular customers are regional managers, this form would be helpful
if it could be active from a mobile device.
We have seen other active PDF forms, but they had pictures, and a lot of
other information on the form that we already have in our catalog. So we
are looking for something simpler.
Any suggestions?
--
Thank you,
Mike Muscat
2550 Okeechobee Blvd
Suite E
West Palm Beach, Fl 33409
O. 561.697.2380
E. cstwpb@comcast.net
www.CustomSignsToday.us
Please proof carefully, spelling, phone numbers, addresses, etc.
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Your design proof and two corrections are included in your setup charge.
Any additional proofs may have additional charges.
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...

Are you looking for something like this?

https://form.jotform.com/53017512696961

I have used separate Check Box and Drop Down fields for each line. The form can be also converted into fillable PDF.

If you need something similar, we can provide you with further instructions.