I recently made my own remote for my 350D. Numerous people have built their own remote controls, but all the designs that I have seen use two separate momentary switches to control the auto-focus and shutter action - both of which are handled by the single shutter button on the camera body itself. Rather than have two separate buttons for activating the auto-focus and the shutter, I wanted to reproduce the functionality of the camera body shutter button, and have a single button, with a half-press controlling the auto-focus, and a full-press controlling the shutter. My total cost was $1.30, and that was for the 2.5mm stereo plug (as everything else was scavenged from various appliances and other devices). See this page for wiring and construction details of the remote. Cheers, Martin.