A very niche market. What scale and gauge ? There are some mainstream products in OO made by Bachmann.and EFE. There are some 3D printed items of tube stock appearing on the market - see ebay - find out if the makers will be willing to scale to your needs but you will be looking to pay ££££££'s, especially if a commissioned design. In the past there were OO models of the battery locos you want made by Harrow Models, in white metal, I had one of those. Company is long gone but somebody might have picked up their tooling. You might want to ask the LT museum's curators/commercial dept' at the Depot at Acton Town. Max