My most significant do-it-yourselfer is the mount I rigged up on my commuter bikes for using a Dinotte taillight. The Dinotte 140 is an incredibly bright LED taillight, but is designed to mount on a seatpost, which creates problems if you carry your gear in a seatbag like many commuters. Dinotte does not offer a stay mount, so I have rigged up several options for mounting the light on 1" PVC pipe. The attached photo shows the light and PVC mount attached to the Carradice Bagman rack on one of my commuter bikes. I have since replaced that mount with a short section of PVC with an end cap that is screwed onto the braze-on mount on the left seat-stay on my bikes. I'll post a photo of that later.