Although this is a cool DVX100 accessory, I always get a little squeamish when thinking about fudging with electronics on anything. But for all you DIY filmmakers out there who are electronically inclined, you'll appreciate this neat little gadget. Equipped with a start/stop record button, this remote zoom control can be made for under $10 according to designer Jared Land. With the available instructions and photos, you should have no problem getting your DVX remote zoom on.
DVX100 DIY Remote Zoom Control

Here's a cool DVX100 accessory - The Disposable DVX100 Sunshade from Desktop Creations! Made from hard paper card and glue, it's a nifty and super-inexpensive design that looks great and keeps the glare out of your lens. Not only are step-by-step instructions and photos given, but best of all, the designer gives you ready-to-print templates for you to cut out so in just minutes, you'll be ready to shoot your outdoor scenes.

This great functional piece of DIY moviemaking gear is an awesome find and can be made for next to nothing! A friend of mine used this template design but instead of using hard paper card and glue, he used cheap plastic folders and velcro which worked beautifully.
The Disposable DVX100 Sunshade | Template 1 | Template 2 | Template 3

If you haven't already seen it, here's the world famous $14 Steadycam known to DIY filmmakers worldwide - the homemade version of the expensive Steadicam. One hour of your time, and about $14 worth of materials are all you need to make it. With step-by-step instructions with photos and demo videos, this is one piece of DIY film production gear that YOU CAN AFFORD! The real ones are upwards of $2,000.00! Unreal.

The plans are free but if you'd like to forego the hassle of making the Steadycam yourself, than you can also purchase one that's already made from the designer Johnny Chung Lee for only $39.95. Compatible for the lighter cameras like the DVX100, PD150, Canon GL1/GL2 and the JVC GRHD1, the site also describes other compatible cameras and what's included in the ready-made kit. Even in DIY indie filmmaker terms, that's not too bad for a huge chunk of production value at any movie budget level.
The $14 Steadycam | Purchase the $14 Steadycam

Made for wedding videographers at Ramasola Studio, this plywood skater dolly photo shows a DVX100 camera sitting on top of it but I'm sure that any camera dove tail threaded hole or universal camera thread would work with this design. They provide some photos of the assembly and give a diagram about some parts and dimensions, but overall it looks a little intimidating because there aren't any in-depth steps to building the dolly and you'll probably need to get your hands on some serious tools. A sleek DIY skater dolly design, though, I'll give 'em that.
Plywood Skater Dolly

The design for this push dolly is very simple, clean and effective. Made for about $75 in materials (mostly PVC pipe and joints), it looks sturdy enough to handle the weight of even the HVX200. The designer also gives some notes about the construction of the dolly including the preferable type of PVC pipe.
Light-Duty PVC Track-Based Dolly

This simple jib is designed to mount directly onto the head of a manfrotto/bogen tripod. Made of lightweight aluminum and wood, it's specifically made for the DVX100 camera models. No plans are given, but the details photos pretty much give you what you need.
Rockford Images DVX100 Jib/Crane

This design is AWESOME! Very original and ingenious, it looks pretty heavy, but sturdy as well. Designed to hang over the driver or passenger side of a car, the design looks like it supports a DVX100 well, but not so sure about an HVX or the heavier cams. Definitely one for an intermediate scale production. Kudos to the designer! No plans are given, but the photos are a big help!
Car Roof Camera Mount

This DIY matte box fit for the Canon XL1 was made for less than $10 using simple items that can be picked up at any arts and crafts store. Made of rugged cardboard and glue, it's a bit crude, but hey - it's a DIY matte box AND for less than ten bucks.
Canon XL1 DIY Matte Box