The arms and machines for manufacturing most likely came from Iran via Egypt as did disassembled rockets and a few drones. This was neither bribery or wink, wink from higher-ups in Egypt as quid pro quo for quiet in the Sinai.
Keep in mind that travel was allowed out of Gaza through Rafah or through Gaza Tunnels to the Egyptian Rafiah.I think training came from Hizbullies and that is why the Hamas savages are upset that Hizbullies did not open up a second front.