Hi they are quite complex to make to a good standard. also you will find the metal would be quite expensive as you have to buy a whole sheet so most would be wasted if you made a single instrument...
they also need quite a few decent power tools and a gas welder all of which cost a lot for a single guitar
however if you have these readily available there are quite a few DIY build threads for basic shapes on other online sites which will aid you if you do decide to make one.
so they are not necessarily hard to make but they do require quite a bit of skill and planning in order to get a satisfactory finished product.
I hope this answers your question?
Many thanks.