Filable PDF creator in Smartsheet

Since the great addition of Document Building, it would be most excellent if Smartsheet also had a way to create fillable PDFs. It is annoying to have to create the fillable PDF outside of Smartsheet.

Speaking of, until this function exists in Smartsheet, what program(s) are people using to create fillable PDF? I have yet to find one that is not excruciatingly painful to work with.