It's important to keep your fluids up through the day. Having a good source of water close on-hand is ideal. Here is my design to keep my 1L water bottle at the edge of my desk.

The water bottle/cup holder clips to the side of a desk via an integrated "C" clamp. The holder supports drink containers up to 80mm in diameter and steadies containers up to 75mm. The clamp adjusts to desk edge thickness up to 50mm. The "C" clamp screw bolt is an M12x1.75mm. I've shared print files for two bolt lengths to cover thick and thin desk edges.

To simplify the 3D printing step, I've made clamp and cup holder two separate parts. The two parts interlock and slide together to form a strong single part.

I've covered the underside of the "C" clamp with a layer of non-slip material to improve the clamp effectiveness and secured the material with CA glue. Layer adhesion is normally the weakest part of a screw bolt, hence to protect the bolt, don't over tighten the "C" clamp.

My print is made in 1.75mm eSUN PLA+ black filament, with 0.2mm layer height and 15% infill on a Bambu X1 Carbon printer. Print supports are required on the base plate when printing the cup. I suggest printing the screw bolt with a perimeter of 10 lines. Parts are by default orientated in the way I printed them on your printer bed.

I hope you can find this print useful, too.

Remember to leave me some feedback or even a tip to keep me enthused to make more of these drawings.

UPDATE
10/01/2024 To help with a snug bolt fit, I've included a revised clamp, 105% larger; as suggested by the audience.