Here's my card.
First detour from the original card... decided on a landscape orientation. Laid out my design then die cut the panel. TIP: Use washi to keep your die in place.
So although on this card it wasn't going to show through any negative, I chose a lighter PP and adhered it to my cardbase. TIP: If you use double sided adhesive, don't remove all the backing. Fold it down only halfway. That way there's less "sticky stuff" to accidentally grab the panel you're trying to adhere while you're lining it up. When the top is good to go, pull the folded backing paper off and press the bottom half down.