I have joined the 501st. My first costume was an imperial officer uniform. This is the build:
I started a worksheet for the parts and pieces I wanted to have. Some of these are not applicable to all costumes.
I wanted to replicate a uniform from A New Hope to get imperator status.
The Unknown Sub Lieutenant that Han shot first when entering the cell blocks was the uniform I chose to replicate.
Unknown sub lieutenant

I started with the boots as many suggest. I picked these up on eBay. They are real leather, equestrian boots. They have a pull inside. Nice and shiny.
I then created my own rank bars with correct buttons and aluminum. I milled the aluminum to allow for flush mounted magnets.
Just for fun I made this. It isn’t accurate, but it is a fun little piece.
Next I worked on the blaster.
I lathed some aluminum and cut it in half for the Power-5 Blaster.
The flash hider is from Dark Energy Creations.
I finished the blaster with a switch for stun/blast setting, a red/blue led, multiple sounds, and a recharge port.
Holster was from eBay.
Belt was BPfau and boxes were made by me.
Code Cylinders from Philo
The Uniform itself was a cosplaysky. The uniform fit without having to order a custom one. I did however have to take in the Jodhpurs and add new snaps.
Finished!