That's a great question, and one we get a lot from municipal clients. The most vandal-proof unit we've ever supplied has to be the "Fortis HD-3000" heavy-duty litter bin. It was specifically engineered for a challenging downtown renewal project.
The key is its integrated design philosophy. The bin body is constructed from 3mm thick galvanized steel, powder-coated with an anti-graffiti laminate. The real innovation is in the details: a single, large aperture with a reinforced internal liner that's virtually impossible to pry off. All fasteners are internal or require specialized security keys, eliminating external bolts for vandals to target. The unit is anchored via a massive concrete-in base plate, making tipping or theft a non-issue.
We supplied over 200 units for that project three years ago. The maintenance reports have been remarkable – near-zero successful vandalism, a drastic reduction in repair costs, and they still look functionally new despite constant use. It proves that with the right material science and intelligent design, you can create public infrastructure that is both welcoming and incredibly resilient.