Transparent layers - part 4

Here are the last of the luscious layered cards.
I know this type of layering is second nature for some of you, but for many others this swap pushed you to try things you've never done before.  This was the first "technique based" swap, and I consider it a huge success.

Four from Marge:

(using watercolors, tissue paper and packing tape transfers)

 Four from Naila:
(using tracing paper, washi tape, transfers)

Two from Nancy:

(using envelope windows)

One from Noel:

(using napking, handmade paper, encaustic wax)

Two from Olivia:

(using wax paper and tape)

Two from Rose:

(using paper from a cigar box.  The scan doesn't show it well, but there is a layer of transparent spider web across the cards)

Two from Susie:

(using napkins, tissue paper and envelope windows)

Four from Terrie:

 (using tissue paper, napkins, deli paper and tracing paper)

One from Tina:

(using a contact paper transfer)

Two from Tricia:

(using tissue paper, napkin and a pie box)

What should our next "technique" swap be?
Got any suggestions?