The [mingw-w64](http://mingw-w64.org/doku.php/download) gcc builds are readily obtained for the modern Windows platform. The [MingW-W64-builds](https://sourceforge.net/projects/mingw-w64/files/Toolchains%20targetting%20Win32/Personal%20Builds/mingw-builds/installer/mingw-w64-install.exe/download) builds are easy to install and work well for building SQLite and extensions for it. You don't need Visual Studio. Even if you wish to use the Microsoft compiler, that can be obtained with the DDK. (device development kit) Building it yourself is far more secure than resorting to using DLL's you might find on the "internet". It's also [easy to do](https://sqlite.org/loadext.html#build), as you can see at the link.