Request for tool supplier

So I've started making buildings using 3/8" square lumber as the frame and I've found my ability to keep the building square is somewhat limited. So does anyone know of a tool and/or supplier that will help me glue my lumber and be squared? Preferrably a smaller tool that I can use to square the inside and something larger to square the outside. I've heard of some machinist tools that can do this but I've never seen any for sale. I live in California so if someone knows a supplier in the states that would be great. But i'm willing to look anywhere as long as it's in english cause I'm an ignorant american

LEGO is your friend

You might be interested in something like the Angle plates or the Magnetic Gluing jig.

Micro-Mark http://www.micromark.com/SearchResult.aspx?deptIdFilter=0&searchPhrase=square

@Trulsa
I've used LEGO on my Hirst arts buildings but when I made a right angle with them I found they still had a bit of movement and it caused a problem when the building got taller. Each level of bricks was a bit more off. Luckily it was a ruined building and I could easily cover the mistake. (actually the building in my avatar) I was using 2 wide LEGO bricks, I wonder if I made it 4 wide that would help. Though I may not have enough, I had to "borrow" from my younger brothers already...

@HornedRat
Oooo thanks again! You are a great resource of knowledge. That site has very cool stuff. Steel square, gluing jig, and angle plates are all what i'm looking for!


Edit: 45min later: I want so many cool things from that site...sigh...someday, someday.