# gdebi will manage .deb dependencies
sudo apt-get install gdebi-core
wget http://ftp.us.debian.org/debian/pool/main/o/openscad/openscad_2015.03-2+dfsg-2+b3_amd64.deb
sudo gdebi openscad_2015.03-2+dfsg-2+b3_amd64.deb

sudo add-apt-repository ppa:openscad/releases
sudo apt-get update
sudo apt-get install openscad