Go back to the person who placed the order.
A loom is lots of sticks and threads, kinda hard to build out of cake.
So you will have to get the customer to spell out exactly what they are really looking for. A small model on a sheet cake? A really good photo on a sheetcake? Maybe some swatches of woven (gumpaste) fabric?
Then you will know better how to proceed. You can find manuals with detailed drawings online, google "loom schematic" or similar.
AThanks will do that..