We used to put our conks in the airing cupboard to dry out and become harder but you eventually came up against one that would beat you. The string was also an important element ... the only stuff that seemed to be readily available snapped fairly easily so we used boot laces which because they were plaited never broke. In the Karting Club run by Edgar 'Taffy' Williams at Westridge School we used to make the kart seats out of fibreglass; the various resins came in blue gallon cans (I still remember the name of the supplier - Trylon) and when mixed with the catalyst would go 'rock' hard. My Mum was a great home baker who had one of those icing syringe sets which I 'borrowed' and filled with some of resin during a club session in the school workshop and then injected a hollowed-out conk to fill the void. When the stuff set a hole was drilled (on Taffy's drilling machine) through the conk for the lace ... and a champion was born. My Mum never did find out what happened to her icing syringe ... all clagged-up with resin residue and dumped in the workshop bin.