Here comes the tender belonging to. US Western train, which is downloaded earlier, see.
I have attached a PDF that you can twist and turn the Tender, in Adobe Reader
I have 3 variants of the lid to the the tender. First the original design, but then you can not place the batteries there. Therefore you have option 2 and 3. Where the variant 3 is a bit increased to accommodate 10 AA batteries. Choose the one that suits you best.
The bottom plate size is 180mm x 80mmm