I got a Contigo travel mug for using when fiddling with the bikes in the garage as normal mugs only kept my drink warm for about 30s.
Mine is from JL, I think.
Molgrips asked a similar question a while back and I suggested this mug to him, saying that I’d take some pics if he wanted. I think he dismissed the mug though as unsuitable so although I took the pics I never uploaded them. But, the mug fits very snugly in my Spesh rib cage bottle mount and has a fully sealed lid that you open with a sprung button on the side.
If you get one, get the plain stainless finish as it can go in the dishwasher; the coloured ones can’t.
I can try to dig out the photos and upload them if you want this evening?