Any advice on cutting aluminium extrusion? Bought 6 1 metre lengths off ebay now I need to cut them down to size. Was planning on using a chop saw and a block to set the length. Thoughts?
You’ll want to make sure the cut is perpendicular as any out-of-true cuts will translate down the line to headaches in building the printer. It’s far from an impossible task, but you do need some care.
Or you could have a 1m^3 printer. 
Or you can use @shauki 's Quadrap design, it’s VERY rigid, and ensures all corners are square. http://4.bp.blogspot.com/-Y8GRa4mq0io/Uz3657PmINI/AAAAAAAADsQ/dtwOJPqqH4U/s800/quadstrap+3d+printer+1.png
Chop saw sounds perfect. I used a hacksaw and a mitre box.
The only issue I’m feeling with the chop saw is a little play in the mechanism which doesn’t inspire me. Perhaps a simple mitre box isn’t a bad idea. A table saw and slide would be nice but I don’t have one (or room for one).
I’ve thought of joining on flats like the quadrap design but I’m trying to make a small 8mm based version and I plan to put panels on it to make a heated chamber when done and that makes it more difficult.
I used a lathe…since its, like, 8 cuts, you might find someone local that could do you a favor if your chopsaw isn’t up to task.
@Richard_Mitchell just take it slow and steady -and anchor the ‘static’ side of your cut so your free hand can control the cut piece. I have had a piece of extrusion decide it was destined to be part of a Tomahawk missile before.
It pays to dial in your saw. I used an inclinometer I got from Rockler -invaluable.
Miter saw and box + clamps to keep the entire thing secured so it can’t move at all would be the best bet. Lacking a miter box, you need to clamp something flat at the cut line as perpendicular as possible and try to cut along that.
@Mike_Miller hadn’t thought of a lathe. Another good idea.
I used my chop saw on my recent laser build. About 40 cuts in about an hour. Went awesome. Just get a good nonferrous blade and your off
@Richard_Mitchell using a lathe depends greatly on having a spindle large enough to accept the extrusion…not a lot of people have access to a lathe, much less one with a big enough envelope. (South Bend 10L here)
I use exactly the same chop saw, but i cut 1-2mm overlength and then face off on a mill to get the ends perfectly squared off. Using a lathe youd need a 4 jaw chuck aswell as a large enough spindle to swallow the extrusion although a lathe would do an qually goood job as facing off on a mill (if not better)…Oh and thanks for the add 
Funny thing that…a three jaw self centering chuck will grab one side in the groove, and the other two flats and make a passible face cut.