Also repurposed infrastructure like water pipes and lamposts. But they had plenty of weapons and explosives pre war, before egypt sealed their border to gaza.
The explosives are the part that obviously should be given the main focus.
And quite a bit of what's being talked about wrt to re-manufacturing Israeli unexploded ordance was stockpiled prior to Oct 7th. Israel did not start bombing Gaza only after Oct 7th (and in fact had been bombing Gaza as late as Sept 23, 2023).
