As a general rule of thumb, wall thicknesses shouldn't be less than 2mm for most commercial 3d printing processes. exception to every rule of course, but it's a good starting point. Most companies will post design guidelines about that sort of thing as it pertains to their process. you have several walls that are between 1 and 2 mm.
I would consider making all the wall thicknesses the same thickness through out.
printing will be cheaper if you get rid of the slab areas and shell them out also, printing cost are determined either by time on machine, or volume of material, depending on company. a solid cube will be MUCH more expensive than a shelled cube-

Also, where you have the chamfers, it gets thin. probably want a matching chamfer on the underside.

This area is a non-manifold edge. the solids areas on each side meat at an infinitely thin line. Many printers will kick this back because it will produce an error in the mesh. you should fix it even if they don't reject it. there should either be some thickness added to where this connection is, or the edge/face should be pulled back so there is a gap.

For high quality prints that I use as an investment casting master, I've been using this outfit-
www.zelta3d.com