I could suggest a material for a Speaker Stand that will be beneficial material if the support structure to be produced from it is produced to be vert rigid structure.
Before considering different materials for a Speaker Support, the Support Plinth itself for the Speaker Stands when done correct, will bring substantial sonic improvements.
As DIYer I find multi tier plinths to be able to really allow the Speakers Cabinetry to get out of the way, in relation to influencing the end sound.