I am having trouble thickening the surface on my design, however i keep running into the error "face which failed to check". I designed only half of the surface and then mirrored it then i knit the mirrored surface and the original together. However i am able to thicken the half surface before mirroring it without an issue. I have also tried thickening first then mirroring, but then i am un able to merge solids. I am trying to thicken the design 0.5" outward if that helps. I attatched my design to see what i am talking about and see if it is just a quick fix. The part is just a part in an assembly. Thanks in advance for any help!