Sprungmonkey said:
what timber does a mash paddle have to be made out of - or rather what timber cant it be made out of?
Any timber that has a strong aroma should probably be avoided, eg Camphor Laurel and Cedar.
Also don't use treated, painted, or oiled timber.
Australian hardwoods are excellent at giving you splinters.
Many health issues related to timber come from breathing dust and fumes.
(I'm not including being hit on the head with a lump of 4x2, which of course would be a significant health issue). So keep this in mind when cutting and sanding.
Any timber products that contain glue should probably also be avoided, because PVA, polyurethane, epoxy, or urea formaldehyde glues are things that could make you :icon_vomit:
Radiata Pine would be as good as any to use, it's cheap, light weight, comes already dressed, no splinters, etc.
Or you could go all creative with Huon, Hoop, or Baltic Pine, or use Oak timbers.