Congrats on your new amp.
I have a previous WW model, but to my eyes, the more recent WW amps, mine included, are all about the same dimensions.
I use an off-the-rack padded gig bag that costs less than $40 I got from SameDayMusic:
World Tour Strong Side Equipment Bag Various sizes are available.
It works great and is near a custom fit.
You might be just as happy to wait until you get your Walter Woods amp, measure it, then order the closest fitting gig bag from Same Day or another similar retailer.
Hope this helps,
--Joe in San Diego