Synthetic rubber might be what we call sillicon rubber as used for bath sealing etc, see B&Q for colours and "clear". Overnight drying and smell of vinegar. Instant cement I think is just as George suggests ,cyano. I`d suggest the Medium for ease of use and a bit of gap filling plus a little more shuffling time. Epoxy I`m sure you know about but if you can find a contact in "industry" that could get some of the small sachets of 10 minute heavy duty stuff. Finally I think I`ve found the answer to a post I made about an adhesive for sticking the lids on 35mm film cassettes. I`ve experimented with Foaming PU glue from
www.falcon-aviation.com It seems to have worked and I only need to find out if it is nitro-fuel proof. Its use on a military tank might make some authenic looking "welds" as it bubbles a bit during the cure on the application of a little water. A lot model shops stock "DeLuxe Materials" which are aimed at modellers and can advise for specific uses. Tamiya just want to sell you another product ! Happy building.