Hi Jerry,
Any custom case maker should be able to make a case to your spec. Our store uses a company over here, gothardflightcases.co.uk and they have made several cases like you describe over the years for us.
I would suggest you contact a case maker, and see if they will do one for you. With our supplier, we need to give him a rough drawing of what we want, he gets the measurements for all the bits of kit, comes back to us with a price for soing it, and then makes it once we give him the order.
John
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Roland G-70, FP-4, BK-7m, SonicCell, KC-350 x 2, DS-5 x 2, A300-Pro, Sonar X1 PE, BR1600CD
Yamaha HX-1 System 1, KA-20x2