This is a spreader bar for a model crane. I designed this to work with m3 screws on the buckles and to be easily printable on an FDM printer, while being strong enough to hold your scale loads.

Make sure you rotate the buckles so they're flat on the printer bed. You can probably print the bar without support, if you trust your printer's ability to do bridging, but I played it safe and used supports. It's meant to be printed right side up, and is fashioned after a real world design that has little tabs to help the bar sit right side up.