TK armor thighs and assembly
There are basically 2 approaches to assembling armor for the thighs. These approaches are often used in the assembly of other limbs as well.
Overlap assembly
Overlap assembly means that the halves of a thigh piece are "overlapping" each other at the seams. Some kits (like RT / FX / AM) were designed this way to make assembly easier. Some troopers prefer to "butt join" the thighs and use covers trips, as this was a more screen accurate approach (see below). With a bit of ingenuity, you can also assemble armor designed for overlap lap construction using butt joins and cover strips.
The overlap itself is usually measured based on distance from the outside "ridge" on the thigh, and cut along a parallel line to the ridge (it's commonly believed that the width of the thigh strip is 20mm on the front and back of the thigh) with the overlap itself facing outwards. You want to assemble them this way so that from the outside, people can't see the glue seam.
Some other methods suggest the use of velcro on the back of the thighs but this is only necessary if you have have difficulty putting on and removing the thigh armor. You can usually glue the front and back of the thighs as it's usually easy to slide your feet in and out.
A more flexible approach is to initially assemble the thighs with a velcro closure in the back, and then wear the armor a few times to see if the sizing is correct. If not, you can reduce it or add shims, then glue them permanently when you are content with the sizing / fit.
Depending on your thigh size, most troopers try to keep the front thigh strip "screen accurate" in terms of size, and if they need to shim the thigh larger, make the overlap bigger in the back (less noticeable). If the thigh armor is not big enough to cover your thigh, then more overlap (more than 20mm) is needed in the front and back to accommodate the circumference of the thigh.
Care must also be taken during assembly to "taper" the thigh more towards to knee, so that it appears that the armor conforms to your body. A common mistake is leaving the knee area too large, thereby requiring padding or armor adjustments later on.
Once the front of the thigh is properly assembled, the tricky part is the fitting. Slip the partially assembled armor over your thigh, and overlap the back. If there is no "ridge" molded into the back of the thigh, take a pencil and make a mark at the top and bottom roughly in the middle of the overlap (split the difference). This isn't where you will cut, you need to make sure to have enough material to create an overlap at the back of the thigh (assembled like the front).
Example of pencil marks showing where the overlap is on the back of the thigh
Butt join / cover strip asembly
A butt join is where two pieces of armor are glued end to end, and a shim is glued on the underside and a cover strip is glued on the outside. This is a more "screen accurate" method of assembling limbs on TK armor.
Most armor makers such as TE2 / AP / TM / ATA, etc. were designed to be assembled with butt joins and cover strips on the limbs. While it takes a few more steps and a little more time to assemble the armor with butt joins and cover strips, many like the way it looks and it's screen authenticity.
Again, most troopers try to keep the front of their thighs closer to screen accurate, and cut material or shim extra material in the back of the thigh, depending on their size.
A common practice is to glue the front of the 2 halves together first, then gluing the front cover strip on. When gluing the cover strips, spring clamps may not reach deep into the thigh armor. Many builders have used rare earth magnets to clamp the strip in place during curing. You can It also sometimes helps to tape the cover strips in place (or use a few carefully placed drops of CA glue or Plastic weld), to prevent them from moving while the glue cures.
Front cover strip being glued / clamped in place
After the front seam has cured, you can move on to sizing the thigh for your leg, and marking the backs of the thighs as described above. Cut away the excess material, and create another butt join at the back of the thigh.
Some troopers will add an "inner shim" inside the armor, covering the butt join. This will add extra strength to the join, since it now has material glued on the inside (inner shim) and outside (cover strip).
If you are gluing innner shims, you can also make assembly a little easier by gluing the inner shim on one half of the armor, letting it cure - then glue the 2 thigh halves together. It's an extra step, but can make for easier assembly.
Detailed Tutorial for assembling thighs with a "butt join"
http://forum.whitearmor.net/index.php?showtopic=11563
Tutorial on how to make your thigh tops "ANH style"
http://forum.whitearmor.net/index.php?showtopic=11836
Adding the battery packs
The "battery packs" are the series of small blocks that surround the lower edge of the right knee on the thigh armor. A detail that many troopers recreate is the "rounded corners" on the lower edge of the battery packs. This was seen in throughout many scenes in the films, including the famous "Move along" sandtrooper scene.
The most common method for attaching the battery packs is heating the strip with a heat gun, and bending it to a curved shape. Once you have obtained the correct bend, you can drill a 1/8" hole on each end, and drill a corresponding hole on the lower thigh armor. Make sure to bend or clamp the battery packs in place, so that the tension of them stays "tight" to the lower thigh.
Because the battery pack is held in place with rivets, it may pivot loose on the thigh. Some builders may choose to apply some glue or velcro to the underside of the battery pack where it contacts the front of the thigh to prevent it from slipping down. Others simply use the tension of the battery pack to keep it in place.
You can use 1/8" diameter rivets, but you may need them to be 1/4" long. You want to put a rivet washer on the inside of the thigh armor to prevent the rivet from pulling out. The thickness of the battery pack, thigh armor and rivet backing washer may necessitate a 1/4" long rivet. The rivet can be painted white after installation to match the color of the armor.
Tutorial for bending armor using a heat gun
http://forum.whitearmor.net/index.php?showtopic=8757
Assembling Greaves / shins
Shins or "greaves" as they are sometimes called are assembled in a similar way to most of the limbs (they can use overlap or butt seam assembly as described above). The only thing that is different is that the shin backs need to be open in order for you to put them on top of your shins / boots.
In the films, the shin backs were often left loose with no closure. You can see this in the "Tantive IV" raid scene when the S tormtroopers blast their way through the hallway. You can choose to leave the backs open or secure them with industrial velcro (*see Firebladejedi's tip below for another method).
Again, most people try to assemble the shins so that they are "screen accurate" if possible in terms of size. If your shin is bigger, you can try and use a more accurate assembly on the front of the shin (using a 20mm to 25mm cover strip or overlap) and make the back of the shin bigger by using a larger cover strip / shim.
You can assemble the front of the shins using the overlap or butt join methods. An extra detail that helps is to make sure that the closure in the back of the shin (whether you are using overlaps at the back or cover strips) is to make sure that the overlap faces the outside. This way, the gap closure or velcro can only be seen from the "inside" of your legs.
Shin halves being assembled with a butt join (inner shim not glued in place yet)
Shin halves being glued together with an inner shim, added inside the armor for extra strength.
Back cover strip being glued onto a left shin
Helpful threads on FISD for shin assembly
http://forum.whitearmor.net/index.php?showtopic=9909
Great tip from Firebladejedi for an innovative shin closure using elastic and hooks
http://forum.whitearmor.net/index.php?showtopic=7123&st=40&p=142828&#ent ry142828
Adding the knee plate
The knee plate is installed on the left shin. The plate itself was designed and formed to fit onto the top of the shin, so other than trimming off the excess plastic, it should fit your shin fairly easily.
Align the plate to your completed shin armor to make sure it fits. Mark the holes on either side where the plate will be attached with 1/8" diameter rivets. To make assembly easier, use spring clamps to hold down the plate where it contacts the front of the shin, and on the sides to reduce any gap that occur.
Mark where you want the holes to be and drill through the knee plate and the shin armor. Install a 1/8" diameter rivet through the hole with a backing washer, to prevent the rivet from pulling out. You may find that you will need a 1/4" long rivet to pass though the knee plate and the shin and the backing washer.
You can paint the rivets white after they have been secured.