The attached file shows a plinth which will hold a display football. If it was just a visual model i would leave it as it is but i want to disassemble the blue and purple triangles so they have the correct cut angles and bevels so the plinth can be made in wood.
The master copy is the design and the secondary copy i was using to try and find the best tool to achieve it.
I tried all the boolean commands but bits were getting left or the wrong bits being cut. I tried creating cutting surfaces and trimming back areas where the triangles intersected which appeared to work and was quite long winded but looking close up at the joins in the wireframe it seemed the triangles werent meeting properly.

Am i using the correct tools for this process or is there another way.

At least some of this is due ito the inconvenient reality of the geometry of offsetting multiple intersecting surfaces. In general when three surfaces which intersect at a point are offset, the resulting offset surfaces do not intersect at a single point. (There are special situations which do intersect at a point. This results in a messy situation when trimming the offset surfaces.

Something is also going on with how you are intersecting and trimming surfaces, possibly as a result of trying to force surfaces to meet at a point contrary to how the geometry works.

Also, be aware that ApparentIntersection=Yes can and will result in trims not being quite where expected.

Another way to ensure planar surfaces from three curves is to create the surfaces using PlanarSrf.

However the straight cuts will result in the edges of the three adjacent offset surfaces not intersecting at a single point due to how the geometry works. No way to avoid it - just needs to be delt with during fabrications. Decide if the inside or outside needs to look better and use for the inital surfaces.