Is there any way to get free shipping on orders of pneumatic system parts?

I saw a guy on TikTok attach a tiny robotic arm to his pull-up bar with zip ties and use a pneumatic cylinder to help with the last few reps at the bottom of the movement. It was janky, but clever! This all got me thinking about putting industrial components together with other components - then other industrial components. Has anyone tried taking a linear actuator and sticking it on a TV mount to make a motorized pull down? Get really crazy: go one step further and unhook the manual knob on the TV bracket, attach a bracket off the end of the rod with a weld, attach to a toggle. I mean, some dude from Alibaba got a $200k grant to work on a tape measure so sourcing a motor from there for DIY could work. What is the weirdest thing you've cobbled together? Also, what are the best pneumatic cylinders for a home gym?