There is no method of doing a save as in Filemaker Go. Now, having said that I'll go home and try it and find out you can... :)
The files exist in IOS but getting to them is beyond Box or Filemaker Go.
What is needed, I think, is a third party app that will copy the Filemaker Go file into your Box folder. Of course with large files you might run out of drive space...
You can always use iTunes to move a file from your IOS device into any folder on your desktop/laptop computer. Be sure to close it first... Not quite what you asked for but better than nothing...
Then there is iCloud where you 'might' be able to save your Go files automatically but I am unsure whether that works or not.
I use DropBox since DropBox will move a file into the Go directory for instant use and I can save a copy of my working Pro file into Dropbox for just that reason if I don't want to use iTunes.
You might also consider using a separate file for your images since you can relate tables in other files, even using several files for images if your solution design might work with separate tables for images such as images of people, images of products, etc.
Using a multi-file, multi-image type design could break your 500 megabyte file into 5-10 files of much smaller size and only files that were changed would need to be emailed, etc. For instance, you may only change a few invoices, calendar entries, etc. and no images and so only need to transfer one 12 Meg file of data only.
Thanks for the response. I'm probably going to be stuck trying to email this stuff and hope it's not too big. It would be great to have a Save option to Box or Dropbox apps.
I'll look into the iCloud idea. that would be another good option in the future if there's no way to make it work now.
A bit later:
I have found that I can both insert and export a Filemaker file from another Filemaker file.
Let's say I have a file on my computer and want to insert a copy of a file on Go....this can be done IF the file is closed on Go.
I haven't full thrashed it about but the idea is to leave the file location empty for the insert into container step. On Go and Pro an open file dialog appears and you can locate the file in question and insert it into a container field.
This has worked over my WiFi connection but I have not tested it with a file hosted remotely over the Internet but I assume it should work.
The file in the container WILL OVERWRITE any file named the same for good or for evil, so be careful.
This is a lot easier than using Dropbox.
When you are finished with a file, insert it into its container field in "Cloud.fmp12". The open "Cloud.fmp12" remotely from another computer or IOS device and click the button to save the file, use the Desktop in Go in your script.
I would test this usig a DummyFile.fmp12 until you have mastered the technique and don't overwrite a file by mistake.