If you do a lot of custom computer builds, you may get annoyed with the price of aluminium standoffs (or you may just lose them a lot). Surprisingly, a bit of nylon tubing makes a great substitute.
DIY blog Curious Inventor shows off a great way to elevate your board if you don't have enough standoffs with you. You'll need some longer screws to pull this off, but you may very well already have some in your toolbox if you're a heavy DIYer. Just cut up the tubing and use it in place of the standoffs. Alternatively, you could use pretty much any kind of narrow tubing (one of their commenters suggests the plastic tubing that makes up ballpoint pens). Hit the link for more details and pictures, and let us know if you have any clever uses for building your own machine in the comments.