I'm trying to get a sense for what options exist for creating large semi-cosmetic enclosures/skins for a consumer product. Let's just say that I've got a product that's roughly 24"x20"x20". The product has an expected life of no more than 15k units, and we're trying to keep tooling cost as low as possible while also maintaining the lowest possible part cost. Annual unit sales would be 500-1000 units. The current concept calls for a single large rotomold integrating a large (5gal) fluidic mixing reservoir into the geometry. The single rotomolded part would contain nearly all visible/cosmetic surfaces, as well as mounting/lead-in geometry for other components and a rigid base plate. The part would also have the bottom trimmed off (straight cuts) and ~16 holes drilled through the walls. Based on our sizing, I'm guesstimating a $12k-ish tool cost (direct draw) with a $40-60 part cost after post-op trimming/drilling. I'm curious what other manufacturing methods could be used for such a part. Because of the depth of the part, it seems that thermoforming or injection molding would require multiple parts attached (somehow) together. Sheetmetal also would probably be prohibitively expensive. I'm not sure of RIM would be applicable because we'd like the component to be chemically compatible (like HDPE for roto), and it also needs to be structurally strong enough to hold a large/heavy fluidic volume. So... any thoughts?