Now for our fundamental length, mass, and time units we can just use the Planck units directly. We will call these units L, M, and T respectively. For electric current, we can simply use charge divided by the Planck time, but we need a charge. For thermodynamic temperature, we need to relate a fundamental constant concerning temperature to the rest of the units. An obvious choice is the Boltzmann constant, which has units of energy divided by temperature.
Luminous intensity is a tricky one.
Then we have amount of substance. Now we can start getting derived units. There are an awful lot of derived units, but only some of them are named. SI arbitrarily chooses current, and so for simplicitly and analogy we will use current as well. The radian and the steradian are technically supplementary units, since they have meaning outside of the unit system.