Haha, I *could* make them out of steel, but I definitely don't have the time for that right now. Making something out of steel instead of aluminum is double or triple the time and hassle. You need to take smaller cuts, it dulls the bit more quickly, and while aluminum chips are friendly little snowflakes, steel chips are terrifying razors.
And frankly, for this application I think aluminum is fine, something like a spring compressor where life and death is at stake is another story. Granted, if they lived in a dealership and got used monthly or weekly or something, the puller would probably eventually become deformed, but if you only use it to preload the rubber like I did I think it would last more or less indefinitely. I didn't need to tighten the bolt too much for it to do it's job, it just made the work of the pry bar that much easier. And of course aluminum threads are more susceptible to cross-threading.
I'll put all the drawings for these tools up on the thread soon, maybe you can find an affordable local machine shop or more enterprising forum member
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