Penloc 1:1 - about 8 quid for a 25ml dual-tube thingumie. They also do it in larger (applicator needed) sizes.
This is used to bind the skin to an aircraft frame, so is fairly heavyweight stuff - and is also holding a fair amount of Grumble together...
Although not sounding very much, a 25ml tube lasts ages as you really do not need very much at all. Mix it, wait 5 mins - rock solid, fly away...
Google it to find the manufacturer. Crap website, but has a phone number (somewhere in Kent IIRC) and they'll sell small quantities.