Mail box to be added to existing mail box

We need to have an additional mailbox added to our own existing mail box. We are number 9 and we need to make a mail box for 9A who are our tenants, so it just needs to be inserted straight under ours so just a base and a flip to close it, no metal roofing required . We need for you to source the material, similar as much as possible.This needs to be in a similar style to the rest of the mail boxes for consistency. It essentially needs to be able to flip open. Hope someone with experience can help. Price includes materials and labour.