I've made this little thingy to allow constant angle sharpening on Spyderco double stuff sharpener. It has set angle of 15 deg, with knife's grind it should give ~20 degrees per side which I consider best for retouching Your blade (and fastest), just like Your triangle sharpener is designed to work.

You basically snap it onto double stuff, index Your knife and follow this angle. It's not intended to slide entire thingy as it will clog Your sharpener. It makes sure You always start honing at the right angle, and is small and light enough to have it always with sharpener.

I've also made some variations of it:
-Slider thats designed to be sled with a knife (is taller than sharpener just slightly so it does not clog it)
-Version with integrated vertical stand to work like with sharpmaker

Best way to print this thing is giving 100% infill and printing upside-down. It's very tight tolerance so You might have to scale it up 1-2% for shrinkage.