I have one of Hahn Rossman's frame alignment gauges which I like a lot. Note that it has a 135 size which I'll never use (yeah, I know, never say "never") but lacks a 126 size which, looking around my bike "collection," I see I can definitely put to use. I don't know if Hahn ever made a 100/120/126/130 tool, but if he did and you have one just gathering dust in your shop, how about we trade?

You obviously need one of my all spaces gauges. Actually, I decided not to make any because they were going to cost $50, which is out of my budget for a joke. Just looking at it, it may not have 126, which is a pretty big oversight. Although I doubt there are too many builders making 126mm bikes nowadays,

Scotch tape two pieces of 3mm hex key on to the 120 space ?
Or maybe Krazy Glue ?

I actually just used the 120 space yesterday.

Skip- I am of similar opinion and position. I have two of these gages, both are of a production run that didn't have what look like drill holes forming the corners, only the water jet (IIRC) cuts. I think yours looks cooler than mine At one time I thought there was a second gage with somewhat different dimensions cut into it and I also thought I had one, but I guess not. Andy

With a hacksaw and file, you could carefully cut down the 135 to 130, then cut the 130 to 126 to make it what you want.

I have two gauges, one of them is the Rossman. I think Jan Heine was selling those for a while. I'm pretty sure I got the other as a part of a group buy. I think it was made with a water jet. One thing that's stopping me from making my own gauge is that I'm not sure how accurate laser cutting is. I might get one made when I finally get around to making a mountain bike. I'm not sure there is a gauge for that, and all I have is 142mm

This tool can be very useful when used with an alignment table. It makes rear triangle alignment quicker than when using a straight edge instead. I can have these cut and etched in Ukraine out of stainless steel by my friends that make my fixture. That is when their electricity is working. It is surprisingly easy to ship stuff from there to here. It wouldn't make sense to make 3 but if the number was at least 10, then it is doable. There are a number of questions that wuuld need to be figured out. I would prefer it come with its own stand instead of having to use a serrate height gage to hold it. I'm always looking for ways to get money over there. And as any economist can tell you that money stays local. The company pays the workers who turn around and pay for local items and expenses and so on.

A decent shop ought to be able to provide very accurate cut, the machines are very precise, trick is adjusting files for kerf width of the laser. A good shop will know what the required off-set would be to make cut file match spec'd dimensions. When I was doing this with acrylic I think I had to off-set .02" to make cut accurate dim. I am assuming the Rossman was made on a router/spindle CNC. The "drill holes" in the corner are how you would set-up the file to allow the machine to create right angle corners without leaving curved inner corner resulting from the dimension of the bit you are cutting with. The CNC router/spindle is accurate at least to the thousandth of an inch and will happily cut aluminum. I have less experience with waterjets, we did order a few pieces but there accuracy was not important.

When I posted before, I was having trouble contacting the company I use. They say +/- .005" tolerance, which is good enough.
Too bad we never do meetups, seems like shipping makes this a pain.
When I was looking at my uploaded designs, I realized I had one with 100/110/130/142/148. Not what OP was looking for, but it's the spacing I'm most likely to use. I think it would be too unwieldy if it has too many more "standards" included. I think it wouldn't take me too long to add 126mm.