Synthetic fiber (i.e. Polyester) is drawn out like viscous strands of honey from a solution (PET). You can import this fibre or make them locally two ways.
1. One is to melt imported solid PET "chips" and then make fiber. Or,
2. You can go the costly route (like China and India did, because of local demand/volume) which is to make PET solution (then fiber) from two different Chemicals using a chemical process (chemicals which the SAUDI ARAMCO or the Chinese can supply among others).
1st route is easy (already done in Bangladesh by BEXIMCO and a half dozen other companies for two decades now), 2nd is significantly more capital-intensive.
There are also companies making recycled PET fibre from plastic disposable water bottles.
A Bangladeshi company for the first time is producing and exporting polyester staple fibres recycling plastic bottles considering the growing market of man-made fibres in the global textile industry....
www.newagebd.net
Bangladesh was on the verge of going the 2nd route twenty years ago, then stopped (JV with Marubeni). Huge outlay and the PET fiber volume back then did not make sense, while it does now.
Maybe one of the conglomerates will invest now.
Engineering products (I'm guessing you mean industrial heavy engg. products, which are typically large one-offs) like 2000 ton cranes, ships, barges, personal watercraft, some plain quality lathes, power and distribution transformers, switchgear, large metal warehouses, lifts, AC/DC motors of various types, Diesel Power generators etc.). Those are only the things I can think of. With every decade more and more import substitution heavy engg. products are made locally.
Lot of engg. products cannot be made cheaply locally because volume pricing overseas is cheaper (more demand). No one can beat China, not even India. They tried and failed big time.