I made a block with 12 fabrics meeting in the center. The center was bulky, but I was able to quilt through it with the walking foot just fine. Once it was layered and finished, the bulk wasn't noticeable. You can also use a clean sledgehammer to pound the bulky centers. I tried it on some of the blocks and noticed a little bit of a difference. I did put a scrap piece of fabric over the quilt to protect it just in case.
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