Resin is a perfect material for molding. It cools and hardens at room temperature and it is also readily available from your local hardware or hobby shop.
With resin, you can also easily copy non-complex parts like bolts and nuts so you can use them in your projects. But working with resin requires a bit of knowledge if you want to be successful with it. It can be quite finicky and you might end up with undesirable results.
Here is where this DIY video comes to the rescue. It is chock full of tips and guides on how you can work with resin in molding projects.
Image source: Brick In The Yard Mold Supply
Move on to the Next Page video: Molding & Casting Tutorial: Resin Casting Tips.