Light Stake Extension

I bought a bunch of solar garden lights from a hardware store. They work fine, but I quickly noticed they won't stand up straight for long, and any little bump causes the light stand to break from its in-ground stake. This is because there is only 18mm of "hold" between the stake and the light. The plastic is too soft.

So I made a stake extension. My first version was a solid, simple extension. To my surprise, it melts in the sun and bends over (See pictures).

What it needed was some solid support. I had some 5/16" all-thread lying around, and simply added a simple 6mm hole through the center of the stake. I then cut the all-thread to about 10mm longer than the stake (since the SCAD is parameterized, yours may need to be longer) and twisted it in. The extra 10mm is so I can hold onto some part of the all-thread while screwing it into the extension.

In the pictures, you can see the actual light and measurement of the stake end. They also show the assembly process. You