I did the door seals in my darkroom with the metal and plastic things from Home Depot for sealing out drafts. The plastic bead on it presses against the door when closed and makes a perfect light seal. To install it I just shut the door, held the bar against the door frame with the seal in place on the door and pushed it a little for compression, then screwed it into place. The bottom of the door got a sweep, basically a bar with a flap that drags the floor and a metal threshold that the sweep seals against. That left a few leaks that were shut up with foam weatherstrip in the corners at the bottom. Works really well, looks good and I don't expect it to wear out any sooner than I will.
I also use weather stip, which worked well until a four legged friend thought is was fun to play with. Thinking about taking an old bed sheet folded and hanging over the door way. Right now, it is used at the bottom of the door and works very well.
I just did mine by painting the edge of the door black and using a V-shape plastic weather stripping. Still leaks a little, but I think there is more light coming off the timer than under the door. In my younger, cheaper days, I closed the door and rolled down a piece of black cloth. When all else fails, close your eyes.
Thanks for all the advice, given my doorway I think that it'll be weather strip, black paint and a draft dodger. If that fails then I'll have to rely on closing my eyes, thanks for that tip loose gravel, don't know why I didn't think of it before. :-)