Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:3155152.

Warning! Make sure your printer can handle long bridges before printing!

This is a three shelf model measuring 250 mm wide 150mm front to back and 100mm tall.

I would suggest printing with a brim.

Other than that no supports are needed,

I've added two support pillars in the middle that can be removed afterwards.

Much bridging will be done and the underside may not look pretty!

The side walls are approximately 2mm so bear that in mind if scaling.

It may be a long print.

I would suggest

.25mm layer height 1.2mm shells 1.2mm top and bottom. 20% infill