A much simpler way is just sell the model under your own name - make it clear the model is for charity so everyone knows. Then just donate all the income raised to the charity.

If you have something like Gift Aid in your country, make sure when you donate you fill in the form, that way the governent don't tax the donation.     

Thats whats I'm doing right now with a model, selling it at various store, not just one.
This model is being sold for the BBC's Children in Need. 

 

Pinky - you left the lens cap of your mind on again.