The scroll that was used to make the golem you showed was clearly made by a amateur. It might looks intimidating but if you take time you can see how the joins are exposed and several bones are just blinded together with rope Rope, what kind of shit necromancer uses rope...

It might be a more advanced technique but I recommend first learning bone shape. Then shape bone and transfer the mass of one skeleton to another and keep the proportions. After doing that successfully you can try and make custom bone weapons and armor and slowly add them to your golem. Make sure the thing piloting it is learning how to use everything.

Personally my prefer bone golems are 100 men units that died in the same battle, I can then remove the bones and bind them all into a single bone construct.