It is usually advised to buy local coral beads (cost about $10), which are sometimes painted in a variety of bizarre colours, but such a gift will not make a big furore when you arrive home.
But ..to bring a part of the ship engine from the ocean-going vessel and put it on a pedestal at home is not a bad idea.
You have to go to Chittagong, one of the world's largest ocean ship scraping and recycling sites. They are brought here from all over the world and left to rust for years in the coastal waters. The stuffing engine is pulled out and dismantled into pieces by the locals.
This is called as Prime Shipbreakers where hundreds workers will cut every piece of an engine into smaller pieces just like sausage - as much as you need to take it with you.
We did not manage to get on shore and take pictures of the shipwrecks because the territory is guarded by militaries and strangers are prohibited to enter. But we did manage to find a hole, sneak up close and stay unshot.