Download Autodesk Fusion 360. It's free for personal stuff or startup businesses. Very straightforward and they are plenty of online tutorials. I am using it for all of my CNC plasma cutting. It sounds like exactly what you want since you can grab a dxf from the faces and save for use in a water or plasma, which is exactly what I do with it. It also has CAM built in, so you can learn that portion of it down the road if you want, which is the whole reason I started using it. Very good program. There is better different stuff out there for certain things, but not free and not as simple.
http://www.autodesk.com/products/fusion-360/try-buy
What is your definition of simple? A bracket with some holes in it you could do in seconds and then instantly export to dxf. Once you use it, you'll be hooked.
IMO, sketchup ***** for actually building things. It's fine if want to use something to get dimensioned drawings or architectural things, but it does not generate parts or dxfs well. It's not really a CAD program designed for manufacturing. The only other program I would consider would be Solidworks, and that is definitely not free.
https://scontent.**.fbcdn.net/hphotos-xft1/v/t1.0-9/11698564_10153435748174168_2293295375398144757_n.jpg?oh=de8593dfc4dd1242b706b46e3d7bea15&oe=5654678E
https://scontent.**.fbcdn.net/hphotos-xpf1/v/t1.0-9/10952544_10153055896409168_7093816382546845574_n.jpg?oh=4b46b18dde312070debaffd90095ca96&oe=5647CE35