I use the conduit system but use a glued conduit end cap at one end for greater security. It is a pain if an unglued end cap ( or cork ) pops off and the whole lot ends up on the floor.
As conduits are available in a wide range of sizes ( for electricity, telecommunications, water and drainage ) and can be cut to any desired length they can be used to store a wide range of materials.
Also, if you glue a cap to each end and then cut the tube in half lengthways they can also be used for open storage (in a suitable rack ) for smaller material such as threaded rod and small section tubing. I have seen this idea described before but I am not quite sure when and where.
Pero