How to get all builders with free gems in Clash of Clans easily?

Oh my, I am still stuck with Clash of Clans. It should be the longest online multi player that I have even played. If you had played it, you should know that it takes time to build and upgrade all the buildings and defences. And you need to use gems to buy more builders to speed up the game. You can either buy gems with real money or get them for free by accomplish achievements given. Is there an easy way to get free gems? Yes, and I am not taking about hack but real effort. Of course, it will take some time and strategic too. That’s the way the game should be played, right?

Clash-of-Clans-Gems_01
Crystal League on Town Hall 6

Clash-of-Clans-Gems_02
Attacking town hall with archers

I got my 3rd builder by using free gems from ‘Sweet Victory! – Achieve a total of 1,250 trophies’ achievement. 4th and 5th builders will need to get from League All-Star achievement because it has the most free gems. Of course, you can get them from other achievements too. But slower.

Getting into Crystal League by attacking ‘farmer’ (town hall outside walls) is easy but time consuming no matter which town hall level you are. Reach Master or Champion League with this method is almost impossible because less and less farmer on those leagues. I failed to reach it for the moment. Maybe some other time…