My family was involved in the rather arcane business of making varnish when I was a child and growing up. One of the interesting phenomena (to a child back in the 1950's at least) was seeing 55 gallon drums of resin being hacked open by the workmen, and large chunks of solids being dumped into the cooking vats. Huge chunks of solid resin were available to play with, since we were the owners' kids, and they were about as hard as you could ask for. Two month old resin is solid enough to last indefinitely. Sorry about that.
But it’s not hard enough to imitate amber successfully. You really need a very long time for all the proteins to fall into place.