While building my own DIY CNC, I needed to cut some T-slots on the table so I can fix some clamps. I decided to design a new base plate for my Makita RT0701C so I could cut the slots equally spaced 3" apart. In the process of designing the base and after printing the first one, I found out that the hole pattern is not totally symmetric and the cutting tool is not centred between the mounting holes. I really don't understand why Makita would do something like that!. So, I reversed engineer mine and created my modified jig.
I posted all the files so other people can just skip that step, there is the original base plate for you to adapt to your needs. Hope it helps!
3 perimeters to give it more strength in case I have to post-process any hole.
I designed this just buy carefully measuring each relevant feature. Along with the STL files, you will find a PDF with the complete drawing for reference and all the Fusion360 files.