This is an OpenSCAD project for a replacement cap of the Quechua 500 bottle.
Main object is in Quchua-bottle.scad, open it in OpenSCAD and render it with F6 and export it with F7.
You'll need a plastic seal of 42.5mm diameter and 1.5mm thick with a hole of 33.5mm diameter inside. You can tweak theses measurements in the file.
// Epaisseur du joint
sealThickness = 1.5;
// Taille du trous du joint
sealHoleDiameter = 33.5;
// Diametre externe du joint
sealOuterDiameter = 42.5;