I wanted an aerodynamic cycling tool box to replace the fabric one, I couldn't find anything commercially, so designed this.

Design Concept :

Designed to fit directly over the seat post with no clips or screws, suited to a Giant D Shape seat post, and designed to fit my Giant TCR 2022 version bike. The hinged lid is fixed with 2 self tapping screws, the model includes some pins to fit through the hinge, but they did not work very well, so the screws worked best.
There are 2 circular indents for small 5mm round magnets to be glued in, I used epoxy resin which held them in securely.

Print Settings:

0.2mm layers

Supports Enabled - Tree (Auto)

15% infill density

Print Lid separately to Box, only print pins if you cant get screws to suit.

Print Time : Box 6h 7m , Lid 1h 27m, using Creality Hyper PLA for both

Improvements:

The box isnt perfect, the closing mechanism needs improvement, and the holes to go around the seat post of your bike should be in a softer material, such as a TPU insert.
Use insulation tape to protect your seat post before fitting the box.
A foam liner, or a TPU printed liner is recommended to stop items rattling about in the box, I used a plastic bag wrapped around the items in the box.

Aerodynamic Bike Box for Giant TCR D shape seat post

0.2mm layer, 3 walls, 15% infill