AM8 - Reinforced X Tensioner (using motor pulley)

*Note: This is only a tiny part of my AM8 upgrades. You can find the links to the other parts at the bottom of the description. There's an upgraded x axis available, made especially for this tensioner: https://www.thingiverse.com/thing:3016379*

About
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This upgrade was made because my toothed 16T idlers were dying away very fast. I was looking for a more robust, easy to build and rigid solution for a proper X tensioner. I made two versions: one is symmetric (idler sits symmetric betw