Are you running the simulator on a like Windows 10 or 11? Are you using the original MSTS or Open Rails ?
The Shape File Manager is a compact and portable tool. It leverages existing MSTS components, so proper placement is key. msts shape file manager 2.5
Managing these files manually is notoriously difficult. That is where comes in. Created by Paul Gausden, this lightweight utility is an essential tool for uncompressing, editing, and optimizing MSTS shape files. Are you running the simulator on a like Windows 10 or 11
If you are kitbashing or creating a new livery (skin) without overwriting the original model, you can change the .ace texture files the shape looks for. Click on after selecting your shape file. A list of all .ace files bound to that model will appear. msts shape file manager 2.5