I noticed in the comments that several users had requested that this design be split up so that a single nut and/or bolt could be printed.
It has been almost a year and the designer never responded so I figured I would upload the requested STL's.
I would recommend printing the bolt upside-down, and with supports from the bed only.
I DID NOT CHANGE THE DESIGN IN ANY WAY, ALL CREDIT GOES TO THE ORIGINAL POSTER/DESIGNER.
If the original designer ever uploads a split version, or if he/she would like to simply add these STL's to his original post (no credit is due), I will happily remove this "remix".