Miners can b built in India. Globally several SUPERCOMPUTERS have been built on computer Junk-waste. Hundereds of 286 / 386 / 486 Systems are connected in PARALLEL to create a SUPER-COMPUTER. India has tons of computer Junk waste which can b used by school / college students to build an Educational Project- A SUPERCOMPUTER, A BTC MINER
It may be a nice college project. But the issue with 486 machines is that their computational and power efficiency is nowhere near the current ASICs. So even if you get them for free, you will be running in loss from day 1 if your objective is Bitcoin mining.