Strongly recommend multirust. It can eat a bit of space if you end up with both stable, beta and nightly installed (but that can still be a good idea -- obviously lots of new projects will experiment with some new features). But multirust takes a lot of cues from other similar tools for sandboxing. I just did:

   $ multirust update
   $ multirust show-default
   multirust: default toolchain: stable
   multirust: default location: (...)

   rustc 1.5.0 (3d7cd77e4 2015-12-04)
   cargo 0.6.0-nightly (e1ed995 2015-10-22)

   $ multirust list-toolchains
   beta
   nightly
   stable

   $ du -hs ~/.multirust/
   996M    /home/e12e/.multirust/