Anyone tried a ‘growing vase’

[Subrosa]

You're talking about a flexible sheet of plastic, cut to shape, rolled into a cylinder and secured. The hard part is getting plastic flexible enough to roll into a suitably sized cylinder without it cracking. The thinnest acrylic sheets, readily available at home centers, with a bit of heat applied while rolling will definitely work for making cylinders. Whether you can roll them tight enough for your particular set-up without cracking is something you can only learn by trying. The hard but still flexible clear plastic often used as a backing material in adhesive applications would be perfect if you could find it in sheet form, as it would be flexible enough to roll into quite small cylinders.