I needed a holder for my 40oz hydroflask that sits beside my desk and not on top of it. I have a small and tight space so my table would always be a clutter. I designed this to help clear my table as well as having a storage for my water bottle. Fits the aesthetic as well. 

As for slicing the file, The overhangs on the top of the holder should be supported. But creating automatic supports causes all the overhangs in the model to supported, causing issues with threads. I suggest manually painting a support area using the highlight and fill tools. As shown in the photo, the tree supports avoid the internal threads of the holder. Threads dont need support as the cooling of A1 printers are adequate enough.

Happy Printing!!