Enlarging pocket in polysurface

This is probably easy to do for someone who knows Rhino, but I’m struggling a bit.

I have the model shown in the attachment. (model file also included). I now realised the square pocket should be slightly larger, but everything I tried to enlarge it failed. I can create the whole model from scratch quite quickly, but that would be missing an opportunity to learn…

Can someone point me in the right direction please…

Block.3dm (646.8 KB)

Extract the vertical walls of the pocket, Scale1d to the original height, scale2d in the top view to the new size. Get rid of the fillets, scale1d the outer box to the correct height, call PlanarSrf on inner and outer top edges. Join all and fillet.

A general tip is to save geometry before you start adding fillets.

Thanks Wim. That’s exactly what I was looking for.