I just got a picture ledge with a lip, at IKEA, and hung it myself! It holds all of my regular use rulers, about 12 of them. Some specialty ones I rarely use are in a drawer with other rarely used items.

I too live in a Cape style house and the walls of my sewing room are all angled except for the dormer and wall where the door is. I have given serious consideration to trying to find stretchy cargo netting and tack that directly to the ceiling. Right now I have a few short shelves that the hubby made attached to the wall (I will go and take a pic later today for you) but it would be convenient if they were on the angled ceiling.

I'm thinking the wall you refer to is the one that slants in from the short side wall up and up to the ceiling? Not a normal vertical wall?
The magazine rack would probably work. I'd also consider a holder that you slide the rulers in from the side instead of the top as normally done. Perhaps mount the magazine rack at an angle. Maybe use hooks or a rail & hook system for the rulers that have holes (or drill holes in them) and let them hang freely. Or at least for the small rulers, so they don't smack you in the head.

Very functional and sweet, too!

They would be over my cutting area. Thus, no head smacking and handy. I like your from the sides idea. I can drill holes in flat metal bars, then screw flat bars perpendicular to a piece of wood then bend metal to make a u shape higher on side further from wall then nail wood into studs… maybe, just for some really long ones I have….

On the slanted wall, ceiling not a letter holder with slanted sides. More a narrow box rectangle, the straight sides keep rulers parallel to the slope not sliding out. Thanks for helping me figure this out.

I figured out how to not have to take a dozen items off to get to the one in back from my stand. I put desk clamps on each one and all I have to do is unclasp and leave the clamp on the rack.

Give it a try. I store my rulers under our living room area rug. I know, I know, I could trip on my area rug...but I love it and my rulers are safe, plus I know where they are.

for smaller rulers you can use an office stationery holder - hang on a wall or stands on counter with multiple pockets angled so you can see them all. I prefer the wall hung one because the counter stand can tip over with the weight of the rulers. I have most of mine stored behind a storage bin on my counter - pulled out just enough to see the width of the ruler.

If it works for you, then great!
I wouldn't be any more worried about tripping on the rug, than usual.
I'd be more worried about the rulers cracking/breaking from walking on the rug.