Depends on what your building out of.. What materials you are going to use.. If its glass most use GE silycon 1 from your local hardeware.. Homedepot/Lowes you know.. If it's acrylic it would in some case be one of the weld-on solvents.. If it's glass and plywood.. Then it would be a combo of silicon and i forget what else...
www.garf.org in th diyt section has allot of useful step by step for you ..