Fixing thin walls with other programs i.e. Meshlab?

Please could you share your techniques for rounding designs to fix thin walls?

I tried rounding a sharp edged model in Meshlab using filters>subdivision>catmull-clark, three times, and filters>smoothing>laplacian smooth

The result is fine except that i have 655 000 vertices, and i want to "merge coplanar triangles" so that the zero detail surfaces become low resolution and the curves stay high res, except I don't know how to do that with Meshlab. Do you have some advice please?

As written on the other thread, I suspect you are trying to fix a problem that is simply not there. The "thin walls" tool works by first splitting the model into lots of little cubes ("voxels") and then checking their thickness against the most demanding limit value, the thickness required for a free-standing wall. It will not recognize small surface details like decorative strips that protrude a mere millimeter, and it will mark all the sharp tips and edges as "too thin" as well.
All these yellow markings are advisory only - as long as the "thin" edge does not extend beyond about two or three times the minimum thickness there should be no problems with printing.