I'm also strugling with my morning ice coffe in my Twizy. Now I'm waiting for my eBay "multi" cupholder that I intend to mount on the right side of the driver seat link
I'm gonna cut the lower part that normaly goes between seat and center console and mout it with self adhesive velcro
I already have mounted sunglases case under the dashboard that way. I can send some pictures of that and also of cupholder when done.
Here is random picture with intended location