In woodturning field where I'm coming from it is quite common to create spalted wood. Intentionally and by accident
Some woods are extremely easy to spalt. Birch for example. If you take birch down at spring time once the fluids are flowing in the tree and leave a stump on the ground. Turn a stump every couple of days. In less than a month it has been spalted. However, to be able to control the process is very tricky and takes some experiment. Too long and you can grow flowers on the stump. Too little and only the outer layer has spalted.
Maple seems to be trickier. I know that someone has had success by burying maple in wet shavings or smaller pieces in plastic bag with shavings.
In woodturning further processing is relatively easy, you can and should work with wet wood. However I have basically no idea how one could dry those spalted blanks and waste percent is probably quite high.
Interesting thing with spalted wood is that if it gets too soft it is pretty easy to harden enough, for woodturning again, by soaking it in 50/50 water/white glue solution. Wood is put in to the bath when wet and left there for couple of days. Then you can let it dry. When dry even softest wood is considerably stronger and harder.
