Episode 6 focuses on the motor mounting and cowl. I have stopped cutting out holes in the firewall for mounting screws as often motor mounts are different. I print a 2mm solid thick firewall and drill out the required holes when fitting the motor.
For the cowling I have gone with a fairly simple design out of the many Quickie cowl variations but I hope it gives you the idea of how you can combine shapes to achieve the design you want. In the tutorial I also showed how you can go back and change a sketch from earlier on in the design and how this filters through (sometimes it doesn't work out as expected!).