This is the cheapest I have seen around being on ebay delivered is $25.95
Selleys Plastibond Heavy Duty Bog is a high strength building filler designed to support heavy loads, fill holes, cracks and splits in a variety of surfaces including metal, timber, brick, fibre cement, fibreglass, concrete, plaster, many plastics and more.
It is also suitable for repairs to furniture, sporting equipment, cars, caravans and boats and can be cut, nailed, filled and painted.
High strength to fill holes and support weight
Can be cut, nailed, filed, sanded and painted
Does not shrink or crack
No listed end date. This may help others out also who need to bog something up.
is this waterproof?