Which method should I use to create a plastic enclosure? [for manufacturing]

[MGPL]

I want to create a plastic enclosure that looks similar to this one to be manufactured, how would you do it?
I tried many ways to get it done, but I'm still very new to the program. I've create the top frame (without the cutout for the display), and extruded the shape to start on the sides. Now I'm trying to pull off a swept curve (with a spline, aiming for the opposite of a fillet effect). At this stage it doesn't allow me cut too far into the material otherwise I get an error message ". Here's what i did...

Surface-loft (for the surface around the display, excluding the trim contour)

• 3DSketch1(profile) A rectangle with sketch fillets on each corner. I replaced the top and bottom lines of the rectangle to splines so I can get a slight curve on the top and bottom.

• 3DSketch2(curve) A slightly curved spline

Surface-Plane1 (to close off the top hole)
Surface-Plane2 (to close off the bottom hole)
Surface-Knit1 (to close gaps between the Surface-loft and Surface-Plane2)

• Merge entities(checked), Gap Control (for 3 Gaps within)

Surface-Knit2 (to form a solid body with Surface-Plane1 and the result of Surface-Knit1 just so I can do the Cut-Loft)

• Try to form solid(checked)

Cut-Loft (to form the trim around the display, the sides are larger than the top and bottom)

• 2DSketch1(profile) a rectangle with small sketch fillets on each corner. Located exactly where the cut out will be.

• 2DSketch2(profile) a rectangle with sketch fillets on each corner.

• 2DSketch3(curve) a very slightly curved spline

DeleteFace (I'd like to extrude the shape to continue so I need to use the surface-extrude, but can't with that bottom face there, so i delete the bottom-most face.)
Surface-Extrude (with cap. Extending the shape straight down by about 40mm)

• 2DSketch4(A Copy Entities of the bottom-most edges)

Surface-Knit(So i can fillets the edge between the sides and the top of the enclosure)

• Try to form solid(checked), Merge entities(checked)

Fillet (with the edge separating the sides from the top)
Cut-Sweep (to the effect opposite to a fillet on the edge separating the sides from the bottom)

• 2dSketch5(curve)

• 2dSketch6(profile)

• This works only to a small effect... not as much as I need. Upon trying to increase how much the curve digs into the surface i get an error "Sweep resulted in topologically invalid body."

So the sweep cut seems to be crap, so.. let's ditch it. I can use 4 surfaces to cut or something, then add a fillet on everything. What am I doing wrong or what is a better way to get it done?

How would YOU do it?