The Riftbreaker

As soon as you have plans and resources to build any of these weapons, you can save, build 6 of the same ones (provided you can afford all 6), equip them, the achievement will pop, then reload to save the resources.

Build multiple communication hubs to speed up the downloads. Some of these weapons costs Rhodenite and other materials that are hard to get in quantity, others just extreme quantities of uranium and titanium (they all take carbonium and ironium). Thankfully weapon plans download relatively quickly with 5 maxed hubs so check out a couple to see which ones you want to build.

Craft Hammers in Extreme Quality. I found them easy to make when your in end game. Its gonna take about 27,000 Carbonium, 108k Ironium, 14,400 Uranium, 7,200 Tanzanite. I would save before crafting the hammers so that way you can revert to your save with all your resources still intact.