Not the easiest substance to mould. I could only do so crudely but it is strong and can make up an emergency nut by being formed round an oiled (so it doesn't stick) bolt.
This is a lot more moldable. It can also be coloured. No statement on heat resistance. The Website is a bit thin on facts but gets good reviews on Amazon [You must be registered and logged in to see this link.]
Epoxy Putty Milliput
First came across this when I saw someone use it to seal a leaking cast iron radiator. It will seal onto wet surfaces. You can drill and tap it and it is a quality product from my experience of using it. Most Youtube videos show it being used to in modelling as it can produce very fine features so is used in modeling extensively. [You must be registered and logged in to see this link.]
Not certain where you might use these products on a Dandy but they are useful tools. The next plastic product I have no idea where it might be used though the more tools you know about the greater your options.