Need advice on a door

It has been nearly impossible for me to get away from my home to my favorite dark sky site, due to increasing responsibilities at home, so I have finally taken the plunge to build. I am following Scott Horstman's plans and am building a 9'6" x 9'6" roll off roof observatory in my back yard. My location is far from ideal with lots of light polution, but it's the best I can do. I have the concrete poured for the pier, and have the deck almost done. I poured concrete for the corner posts today, and the deck is nice and level and square. I am having a hard time finding a suitably small door here at my local Home Depot and Lowe's. I would like to know how other people have overcome this obstacle. I found one place that would custom make me a steel entry door suitably short for almost $500, but I thought that was a little rich, and they wanted a month to supply it. I'd like a metal door for security reasons. I have not made the walls yet, so rough opening size is flexible. How have the rest of you bridged this problem.

Sincerely

Mike

Made my own! I used 1/8" wood door skins. But sheet metal would work the same!

Hi Mike,
I had the same problem with finding a door. I couldn't even find one to cut down to size because most exterior doors are panel doors with the knob holes already cut in. I chose to build my own pre-hung.
First I made my frame using 5/4 pine and a piece of 2x8 pressure treated for my threshold.
For the door I used 2x4's for the top,bottom, and hinge side. On the knob side I used a 2x6. All four corners were assembled using a half lap joint, Gorilla glue, and wood screws.
The center of the door was filled with 1 1/2" Styrofoam insulation board. I then skinned the door with the Glasteel (fiberglass reinforced PVC) that I used to cover my dome. You can find other materials to skin the door if you prefer.
I installed the completed pre-hung and trimmed it with PVC brick mold.
I already had 90% of the material around the house. My only real expense was the lock set and hardware.

Good luck,
Bob

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If you haven't built the walls yet, why not size the wall height to accept a standard door?

dan