I got the idea for these boxes from some other ones I saw that had diamond shaped holes in their sides. Those boxes had straight vertical sides and all the corners were sharp right angles. So I thought I could use that concept for similar ones that had a more pleasing, organic overall shape.

These 2 boxes are the result. They are very similar; the difference is all the edges on PerfBox1 are sharp corners, whereas they are all smooth filleted curves on PerfBox2. I designed both boxes the same way - I started with a squircle, which is a circle modified to have a shape part way between a circle and a square. Then I scaled that result to be longer in the X direction, so I ended up with a rectangle shape with rounded corners and curved sides. Then I scaled this rectangle shape into 2 larger ones, stacked them up vertically, and used all 3 as control curves for a Loft surface.

PerBox1 printed in a little less than 15 3/4 hours using a print speed of 100 mm/sec and a layer height of 0.200 mm. PerfBox2 printed in 10 minutes less because I used a print speed of 110 mm/sec.