Hi John and Christopher , John have you got an acer ( japanese maple ) flamingo or a salix ( willow ) flamingo ? Christopher - I'm really surprised that you are cutting back an acer as they only need minimal pruning - I've got an acer flamingo and I'm sure if I hard pruned it , it would be no more !
I agree with Jean - Japanese acers do not tolerate cutting hard back, although salix do.
Hang on, I'm getting my acers crossed. Yours isn't one of the small Japanese acers, is it, but a more normal small tree? In that case, you can theoretically cut back the trunk when it is young and thus cause it to produce lower branches and so turn into a shrub. Afraid I've never done this, so can't comment how well it'll work, sorry.
How can I take hard wood cuttings of acers