Shane did a couple of presentations for the SDFWA and shared lots of handy details. Here’s his own video. Shane started doing CNC work and then working with epoxy after he tore a shoulder and had surgery and couldn’t work for months. He excelled at the techniques as you will see. Also, I don’t use V-Carve or any of the software these guys talk about and you are the same just look for the techniques and get a beer when they go on about finding a setting or lots of Vectrics type stuff.
Yeah, I would add that air is introduced into the epoxy when it is mixed too vigorously; better to mix longer, slower. Let the epoxy rest for a couple of minutes after mixing to degas and dust it with a torch prior to pouring. And do all of the above (I use cut Spar Varnish to seal). My experience has been that once the pour is completed, stick around for 10 minutes or so with your torch and lightly dust away any remaining bubbles.
And I would add that the work piece shown is salvageable. Once the epoxy has completely dried, it machines very easily. You could stage sand (120,220,320 etc.) or plane it and then polish it.