Hook: Size 12 Scud/Pupa Hook (perhaps a little big but the size and style of most Czech Nymphs)
Thread: Wine, 8/0
Ribbing: 4# Clear Mono
Weight: Tungsten/Lead wire wrapped up shank.
Underbody: Fine dubbing/Kudra fur (you choose clean non-spiked or with guard hairs)
Shellback: Any foilback or plastic pre-cut or cut narrow.
Thorax: Any dark spikey dubbing. Here, I used a dubbing brush from Angling Specialties/Calif.
You know the routine: wrap thread base, wrap lead on and cover with thread, tie in ribbing and foilback, dub abdomen, pull foilback/shellback over dubbed abdomen, wrap ribbing to thorax (keep foilback on top as your rib), keep thorax area thicker than abdomen, pull remaining foilback over to hook eye and secure, a touch of dark permanent marker to foilback over thorax (optional), finish thread head.
The name Czech Nymph seems to overshadow the Caddis Pupa or Scud qualities. Rhyacophyla, Scuds or any sizeable nymph are easily represented by these edible morsels. As I said above in the pattern, the only part that varies is the dubbing you decide to use for the abdomen. Do you want it non-spikey or spikey. It does affect the nymph or scud look. I believe if you click on the pic you can enlarge and zoom to get the details. Please query Czech (CZN) in the search box, upper right, as I have numerous (20+), excellent postings re Czech Nymphing and related links. Search On! Good luck!!