My flat surface is a 1-1/4" thick piece of granite counter top on saw horses (steel), supported by 1-1/2" oak ply planks. Originally I had a composite slate section from a billiard table.

While a jig is nice, getting some experience building will help to determine WHICH jig is most useful to you. I went the other way around, getting a jig first -- a NorTac model that is quite flexible in set-up. But that flexibility is part of its detriment. It takes quite a bit of fiddling to get it set up. Also, being a plate type, there is very limited access to certain areas.