• PVC tubing -- I bought a 2-foot length of 3" pipe from Home Depot
• 3" PVC plug cap
• 3" PVC female adapter with threaded collar
• 3" threaded plug screw cap
• PVC primer/glue
• Tape measure
• Sharpie or other kind of marker
• Hacksaw and miter box
• 10mm socket and ratchet wrench
• 2 pipe clamps that'll expand to over 3"
• 90-degree angle bracket (ours had holes pre-drilled, which was useful)
• Dremel, if your angle bracket doesn't have pre-drilled holes

background.
The toolkit that comes with the XT225 is like any other bike toolkit I've ever had -- woefully inadequate in both quality and quantity. On a streetbike, this isn't really a big deal, since worst-case, I can call AAA. On a dualsport, though, I need good tools for the backroads. Unfortunately, I can't fit anything better than the aluminum stock crap tools in the stock toolkit box.

I got the idea for this PVC tool tube from the message boards at xt225.com.

procedure.
The 2-foot length of 3" PVC pipe at Home Depot was the perfect length for two tool tubes. I think 9" is a pretty good length for each tube. A miter box is really useful when cutting the pipe with a hacksaw.

The next thing you'll do is attach the end caps to the PVC tube. Coat the inside of the plug cap and the outside of one end of the tube with PVC glue primer. When it's dry, coat the same surfaces with PVC glue. Put the cap onto the tube and press it tightly until seated. Do the same with the 3" threaded collar.

Screw the 3" threaded screw cap into the threaded collar, and you've got yourself a pre-installed tool tube!

Next: installation.

Unbolt the two 10mm bolts that hold the stock toolkit onto the XT225 frame. Hang onto the bolts; you'll need them again in a minute.

Cut the brackets to fit the XT; bolt the bracket to the stock toolkit mount using the original bolts. If the XT's bolt holes don't line up with the pre-drilled holes in your bracket (or if the bracket doesn't have pre-drilled holes), break out your Dremel and make some new holes. Finally, just insert the pipe clamps into the holes already in the brackets (using the Dremel again if necessary).

result.
I think the tool tubes will work really well. I'll update this page as I do more off-roading, but the on-road shakedown test I did (freeway, twisties, city streets) proved this mount is very solid.