Yes, version 4 was bouncy. It was literally my first attempt at attaching the desk and was just a proof of concept. I spent a lot of time making the work surface stable, and I think you can see in version 5 and later that it's no longer an issue. I'll probably make another video to address that issue. Thanks for asking.
If it's reasonably affordable (leather, microfiber, different colored vinyl, etc.) you just tell us what you want and we'll do the rest. If it's highly specialized like your team logo, whale foreskin, etc., you'll need to send that to us. (Two yards is plenty.)
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