I did not know we had so many different species of solitary bees in Australia. So I did a bit of research and bam! Over 1700 different species on this magic continent of ours!
What's common in my area is the Resin Bee and thus I built a bee house that would fit it's desired specifications all according to this link:
It specifies 3mm - 10mm holes and made of any Australian hard wood. We have a mish-mash pile sitting in our driveway from a recent renovation so that'll be our starting resources.
Overall a very fun build and bring on those pollinators!