I have come across on my travels in the UK, a company that produces
fittings/Joints (slip on clamp construction system) that uses a range of
standard size tubing. These fittings are low cost and are normally used
to construct railings, racks, playground equipment, market stalls etc.
They are secured to the pipe by hex bolts. They come in all sorts of
shapes and sizes. You will have no problem building launch pads using
these. Email me for more info.