Examine your plastic sheet for areas where it may not have fused well. If it all looks good, you are ready to use it!
Just behave as if this cool, fused plastic sheet were a regular piece of fabric! It sews right through on a regular machine (won't get stuck or not feed feed properly... it will smoothly go through just like any piece of fabric would!).
When you are cutting shapes out of it, I recommend you draw your shapes on the backside of the fused plastic using a permanent marker (so that it won't smear and get all over you), and then cut them out. Do this instead of pinning pattern pieces to it because wherever you put your pins is going to leave a tiny hole in the plastic.
Just use a regular or universal needle, no leather needles needed... this stuff is actually quite soft and easy for a regular sewing machine to pierce right through!
And if using a sewing machine isn't your gig, try your "hand"... haha... at hand sewing through your fused plastic! I've made some wonderful little accessories by "whipstitching" or "blanket stitching" around the edge with colorful embroidery thread and even yarn!
There are so many possibilities for what to do with this new eco fabric... dream up something useful for your new recycled fused plastic!