Increase stability
To ensure the stability of your fir tree, you can apply some hot glue over the rear interfaces of the discs. This provides additional support and prevents tipping. Optionally, you can also attach additional wooden discs as support.
Creating the tree trunk
For the tree trunk, glue several smaller wooden discs on top of each other. Once you have reached the desired height, carefully attach the trunk to the underside of your fir tree. Make sure that the tree is stable.