Here you can see the screw getting through the foam base.
Now the tree is solidly attached to it’s base.
Without the plastic washer the screw would have get through the foam base.
The roots have now cured and are ready to be glued to the foam base.
A final test to make sure every roots will fit great.
Regular white glue was used to fix the roots to the foam.
Here is the final result. Foam react and melt when put in contact with super glue so it’s best to use regular white glue as it will not damage the foam base.