I designed this bottle caddie to fit Dr. Brown's 8oz bottles, but it also works well for the 4oz bottles. It's primary purpose is to keep the bottles upright while in a cooler and traveling since they tend to spill if they're tipped.

I used a 0.4mm nozzle, 100% infill, and PLA to make this print. I used two wall layers, which ends up making the print about 100% infill regardless of what infill I actually chose. If you're using a smaller nozzle, you may want to reduce the amount of infill. No supports required.

The end result feels very solid and is very easy to grab and hold as a bottle caddie, especially if one of the slots is empty.