We are in the midst of remodeling our kitchen with Ikea cabs and we used a non-Ikea 30" SS apron front sink in a 30" sink cab. We had the specifications for the sink so we brought that with us when we had our design appt. at Ikea. The Ikea kitchen designer knew exactly what we needed, which was a 30" wide, 5" tall drawer front so we could cut it and place it over 20" doors. Here's the cabinet, sides cut to accomodate the sink. You can also see the filler strip we cut from the drawer front. And here's the sink dry fitted:
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