When printing out the original triangle I saw some minor flaws in the underlying STL. Thus I just recreated the file with Onshape - the source can be found here:
https://cad.onshape.com/documents/b89ed99219bb53b080468d01/w/86378783ecb15a490c1a7f20/e/419792bd82ccf04a9fb3b566
Height, sidelength and width are parametric, thus easily changeable. Enjoy