I have some shelving in which the plug-in uprights are 37 mm O.D. plastic tubes, about 420 mm long, probably polypropylene or similar, wall thickness about 2 mm; I would like, _on_a_temporary_basis_, to replace some of the uprights with shorter ones.
Is that anything like a readily-available inexpensive standard size in any suitable material (the I.D. does not matter, except that the wall must give reasonable rigidity)?
To help you to envisage it, that O.D. is about 50% bigger than that of a proper wooden broom- or mop- stick.