Ecnerwal wrote:

A set of large Forstner bits and a drill chuck mounted in the tailstock.
Brief search finds Forstners up to 4-1/2 inches, and they are a lot
faster than fussing with a boring bar setup. There may well be bigger
ones available, the search was not extensive. With a hole of up to 4-1/2
inches to start from, any further hollowing could be done sidegrain
rather than endgrain, and would thus be easier cutting. Be careful when
working with such large bits...


I'm thinking that forstners are maybe too short. I've got the obligatory
set of them and I don't think the shanks are much more than three inches or
so. They'd do fine for shallow objects - I've used them for that - but I've
never seen Long forstners, say 6-12 inches.