For printing I recommend using PETG, especially for the spring. It is flexible enough and not as prone to breaking as PLA.

Print with these parameters:

• Density: 100% fill
• fill pattern: straight line
• generate forced supports

The flaps are identical, always print them in pairs. You can use variable layer height to speed up printing.

I recommend printing the spring with the enforced supports and following object-specific settings:

• External perimeters first
• 4 perimeters
• Paint-on supports
• Paint-on seam

Paint one support under the lower protruding ring to increase print stability. You can use a brim instead, but it is harder to remove and the result will be the same. The material consumption varies only marginally. Next, place two supports to both side holes for the flaps, just on the upper horizontal part. It is possible to print the spring without supports, but there is almost no saving in time or material and the print looks better with supports. Paint the seams along the inner area of the spring. I put one area opposite the side opening and two others at 90 degrees on both sides. This helps prevent the printer from starting in the air. Again, I recommend variable layer height to speed up the printing process.