Brief Army Overview
If you are thinking of making an Eldar army out of only plastic kits, a good Craftworld to choose is Ulthwé. The core of an Ulthwé army are Black Guardians and psykers. Ulthwé also characteristically has very few Aspect Warriors. If you do opt to build a plastic Ulthwé army, you might want to have it led by a powerful Farseer instead of Autarch Ygrim.

For a versatile force, a unit of Storm Guardians (with Fusion Guns no less) can be added to the two units of standard Guardians. If you are interested in fielding a Warlock for your Guardian unit with the Scatter Laser, you can likely skim a few points here and there to make it work. The team of Guardians with the Bright Lance gives you a unit that can shoot straight with a weapon that can take out enemy heavy vehicles. Meanwhile, the Storm Guardians offer you an inexpensive hand-to-hand unit. When commanded by a Warlock with Enhance, the unit has a mighty Weapon Skill of 4 and an Initiative of 5!

Rounding out the Troops are the two units of Dire Avengers. With higher Weapon Skill, Ballistic Skill, Initiative, and Leadership along with better armour (4+ save) and weapons than the Guardians, the Dire Avengers are a great Troops choice for only 12 points per model. A unit of Dire Avengers accompanied by an Exarch with a Shimmershield and the Defend Exarch Power is quite durable in combat. The Shimmershield gives the Exarch and his unit a 5+ invulnerable save in close combat, and the Defend Exarch Power causes enemy models to lose an Attack (down to a minimum of 1) in each Assault Phase.

The Heavy Support units of this army contain two new plastic kits and a Falcon. If you are excited about the deadly Wraithlord, you can substitute in a second one in place of the Falcon. Heck, you can sub in a third for the War Walker Squadron if you really wanted to cause your opponent to tremble before your mighty Wraithlords. As it is, use the Falcon as bait to draw lots of fire while the rest of the army sweeps across the battlefield.

With so many plastic kits, there are a ridiculous number of ways to design a plastic Eldar army. Regardless of how you build yours, have fun grinding your upstart opponents into the dirt like every good Autarch and Farseer should.