Here's a cased caddis pattern I've had lots of success with over the last year. Caddis are an important food source for our trout and they key in on them below the surface just as much as on. The cased caddis is often overlooked but shouldn't be. Considering how much time trout spend on the stream bed it should come as no surprise they gladly eat these bottom dwellers. It's tied to be use as an anchor in a euro set up but would no doubt work well under an indicator also. It has a lot going for it. Between the tungsten bead and the lead wraps it gets down in a hurry. The pearl braid adds just enough flash and the partridge gives it life suggesting movement. The real key to this patterns is the hook though. The jig hook makes the pattern ride upside down. This dramatically helps the fly not snag. Another option would be to use a ball-head jig hook like used on the micro marabou jigs. A straight hook would look fine but snag more although there are ways to make them ride upside down also.
What you'll need
Hook: Dohiku Jig (or similar hook) sizes 8-12 are the most useful
Weight: Tungsten bead (the slotted ones work best with jig hooks) black or copper
also lead or lead-free wire(optional)
Body/tail: Pearl core braid chartreuse or color to match naturals
Case: Hare's ear dubbing
Rib: Webby hackle, brown
Extra: You will need a dubbing brush or velcro
Slide on the bead and run a layer of thread. If you are adding the lead wire for extra weight do so now. If you're paranoid about things moving around go ahead and use super-glue. I find that it's unneeded as long as you use nice tight thread wraps. Only wind the lead back to the point. This keeps it front heavy so as to not mess up the balance of the jig.
Using a lighter melt the tip of your braid. This melts everything together making sure the braid doesn't unravel and in the process makes a dark little caddis head like the naturals.
Tie in the braid. It should be about half a shank long. Clip the waste before you get to the lead. By tying everything in before the lead it will help even out the body.and avoid unnecessary bulk.
Tie in the partridge by the tip. The barbs should extend a little longer than the braid. This is also a good time to cover up the lead with a layer of thread.
Wind on the partridge. Depending on the quality of the hackle one turn is usually plenty.
Tie in a brown hackle so it cups towards you. This way the barbs will slant away from the partridge making it less likely you'll trim you're legs off at the end. I'm using a webby rooster feather (neck hackle I'm guessing) out of a Whiting variety pack but a hen saddle or some cheap strung rooster saddles would work great. Keep in mind you're going to trim this so just use something cheap. If you want to add some extra durability you can add mono or wire to use as a cross rib. I don't find it necessary at all. In fact the more beat up this fly gets the better it usually works.
Dub the case. Don't worry much about taper. Good old natural hare's ear works great. The case on a natural will be more or less the same color as the stream bed so use that as a judge on dubbing color. If you're stream has a lot of vegetation a little green mixed in couldn't hurt as caddis use what's readily available for their case.
Wind the hackle up in even turns. Five is usually about right.
Clip the waste end if you haven't already then whip finish and head cement . This fly spends a lot of time bouncing along the bottom so a double whip finish couldn't hurt. Using a dubbing brush or a piece of velcro absolutely go to town on the fly. Really brush everything out good.
Taking care not to cut off the partridge legs trim the fly. A straight cut on each side leaves you a little box which is what you want. Taper towards the front if possible but the fish don't care either way. My poor photography skills don't do it justice but the hackle rib is what really makes the case.