sandboxie is not seen, but in the most primitive variant - to create the virtual machine
and it was convenient to use (to automate the creation of VM etc), virtual machines, virtualbox is the same, there is a SDK
language - C/C++
can estimate a project like Genymotion is an Android emulator created by this method. IMHO very easy... and is Android there might be the same wind...
yet there are ready-made sandbox of open source... you can take it and finish, even remodel
language - again, C/C++