Squirrel Daddy sells the upper and lower block combo on Amazon for $20. The upper receiver block is a solid piece of aluminum with two notches milled out for your receiver lugs and they use really tight fitting pins with cotter pins to hold in place. The lower receiver block is a solid piece of strong Delrin plastic that fits into the mag well. They worked well for the two AR's I built. Also, make sure you have a good torque wrench for getting the barrel nut on there. You don't want to over or under torque the barrel nut. I would also get some decent punches, and of course an armorer's wrench if you don't already have those. I spent a grand total of $50 on tools to build both my AR-15's. They are pretty fun and easy to put together.