yeah basically apart from novelty ied casing - unless you've got a metal printer there's not much terrorist wise a standard fff 3d printer will help with.

Just make public the recipe for acetone peroxide with one minor change.
Tell the buggers that the mixture should be boiled not chilled and let darwinism do it's bit :-)

And yes it's astonishing just how badly educated most of the authorities are on this kind of thing. Just look at the ridiculous measure they take for airline 'security'.
Most of what you need is already onboard the plane or can be purchased once you've gone through security. taking nail scissors off people and then giving them cans, glass bottles and metal knives once on the plane makes NO SENSE.

Likewise the level of education in the average copper is woeful.

The problem is the people who end up in charge - don't get there because they're clever or well informed. They get there because they can kiss arse really really well. And they're good at filling in forms.

Unfortunately that also goes for most of the technical consultants who make it to the big time as well.