orvil wrote:You can buy a rigid fork from a number of online retailers for about $30 or less. Less effort and much less weight.
lol.. If you're not into replacing parts, you could possibly replace the springs with a piece of electrical conduit. I have no idea what size or length you would need, but I'd be a bit reluctant to spend much on a Granite Peak. A compact pipe cutter and a section of EMT would be about $10... Or, you could just let them seize over time. Rust and dirt have a tendency to lock those forks up after a while, especially if you ride them in wet weather.
Otherwise, you could pop the top caps off, and chink them full of mortar mix, but that would add a few pounds to the front end. Spray foam might do the trick, but spray foam and Portland cement would both hold moisture and the cement could be actively corrosive, especially if there are different metals used to build those forks. Galvanic action accelerates corrosion.
Let us know if you try this, and how it turns out