It's summer, and that means people are getting their vans road ready for the fall climbing season!  One of our additions has been blackout window coverings for those times you need to stealth camp, that also didn't look like we pasted tin foil in our windows.

Insulated Blackout Window Panels tutorial
Before: Classy light-resistant curtains.
Insulated Blackout Window Panels tutorial
After: Custom-fit blackout panels.

You'll need:

Insulated Blackout Window Panels tutorial
We have a Ford Transit 2015, which doesn't have metal trim around the window. I form-fitted the insulation to fit in the small slit between the glass and black plastic border on the inside.
Insulated Blackout Window Panels tutorial
Measure the window's largest dimensions.
Insulated Blackout Window Panels tutorial
Cut insulation to the rough rectangular outline.

Fit it in the window and use a sharpie to mark how much to trim.  75% of my time was spent here getting a perfect fit without cutting too much.  It's like that tale of the boy who wants to make a perfect heart for his valentine, makes a hundred cuts, and ends up with a minuscule size heart.  Anyways, take your time and don't cut too much.

Insulated Blackout Window Panels tutorial
Insulated Blackout Window Panels tutorial
Insulated Blackout Window Panels tutorial
Cut felt much larger than the insulation. Generously cover both sides with spray adhesive.
Insulated Blackout Window Panels tutorial
Press insulation and felt together, working down to make sure each inch is adhered.
Insulated Blackout Window Panels tutorial
Cut the felt to size.
Insulated Blackout Window Panels tutorial
Repeat on other side. 
Insulated Blackout Window Panels tutorial
Now apply bias tape for a nice edge finish. You want double fold bias tape.
Insulated Blackout Window Panels tutorial
Insulated Blackout Window Panels tutorial
Insulated Blackout Window Panels tutorial

I missed a photo of the next step, but you want to fold the very end of the right side over ~1/4" and iron it flat to make a nice edge (rather than a raw edge), then lay the left side on top of it, then stitch the whole thing down to finish, like this tutorial "Joining Two Ends" section.

Insulated Blackout Window Panels tutorial
Insulated Blackout Window Panels tutorial
Insulated Blackout Window Panels tutorial

[Sidenote: You could put the bias tape around the insulation and sew once to catch the top and bottom, but in practice it's nearly impossible to be this close to the edge with a straight seam and catch both sides since you can't see the bottom.]

Insulated Blackout Window Panels tutorial
Insulated Blackout Window Panels tutorial
Insulated Blackout Window Panels tutorial