The author remixed this model.
Increased the dimension of the Back plate to added room for M3 Threaded Inserts. Added Heat M3 Threaded Inserts to the front plat.
Please us original model all other parts & instruction. I'm not yet sure if I increased the bottom of the Back plate too much, but will find out shortly.
Link for M3 Threaded Inserts.
I thank Print.NC for his original model.