Hello, since no one has come forward, let me help with some perspective, with the caveat that I have been a bit out of the game for some time.
You have not mentioned your personal skill level or your budget, both very important to help guide you better.
A fully cooked design that is very well received is this one..
Home > Floorstanding Speakers > The Pit Vipers
sites.google.com
Or if you choose to design your own, then a lot of other variables come into play. Then there is an availability in India aspect..
Some broad strokes
1. If you go 12” than it’s better to look at pro woofers. They are more easily available in India. Look for the dealers of faital pro, b&c, eminence and others. Not all 12” are suitable for bass in home use, many don’t go low or require a big box to do so. Look for a woofer with a low vas, a relatively high qms and a low Fs. I chose the eminence 3012lf (not the standard version) for precisely such a design. A lot depends on whether you will go active or passive and your box alignment as well but that is getting technical. This recommendation is based on a passive design and a bass reflex box.
2. For midrange, you can also look at pro audio and you could easily do 5” as well again, depending on your crossover points from the Woofer and to the tweeter. Or you could look at sb acoustics who have an India dealer. Your mileage with him may vary, some people on the forum swear by him, it I’ve always found him a bit shifty and uncontactable at key times, and could not build up confidence to deal with him. The pro audio guys are pretty professional, but remember, just two woofer or just two tweeters is a small order for them.
3.tweeters again sb acoustics or look at some of the other Indian diy audio sites or import them. Tweeters are easiest to import.
4.box design and crossover. This is as crucial as the rest. Once you decide to design you own, Irrespective of what option you choose, you will need to invest in a measurement mic and an audio interface to use with the pc to do the box and crossover modelling.
Hope other FMs will pitch in…