How to upload .stl files

Is there a way to upload .stl files with a widget? If so, is there a way to upload them into a Dropbox account?

LS

You may try with these widgets that allow to change the allowed extensions: 

http://widgets.jotform.com/widget/drag_and_drop_upload

http://widgets.jotform.com/widget/file_uploader_by_uploadcare

http://widgets.jotform.com/widget/kloudless_file_uploader

You will find the allowed file types on the widget settings. 

You may also use the basic file upload field, here are some guides about how to use it and change the allowed file uploads: 

https://www.jotform.com/help/332-How-to-Create-File-Upload-Forms

https://www.jotform.com/help/29-How-to-Change-the-Allowed-File-Types-in-the-Upload-Field 

I hope this helps.