I am in the throes of designing my amp. I have created a CAD model that is helping me visualize my structure and how it will play into the aesthetic.
At first glance, and every glance thereafter, my design very closely resembles a washing machine made by Mattel. This was driven directly by the constraints of designing an amp cabinet that is essentially a rebuild of the current cabinet. I have added some greeblies, moved some knobs, and added vents (which actually serve a purpose beyond being greeblies), but the overall look is still unbearably that of a washing machine.
I tried darkening the control panel, adding filets to the edges, and changing a greeblie vent for a steel panel (which appears white, for some unknown reason). I do like how the vent on top looks, and I am likely to keep it there, but I will perhaps add a cover to make it look more complicated.
Some of my weathering practice has gone well. I like the look of the gunmetal paint, rust paint, and oil effects on the bumpers that I removed from the amp. On the final build I am planning to make my own bumpers to fit the aesthetic.