I don't travel with OMS - I have just been using pencils to blend themselves... in the past I've brought an alcohol blender pen with me (Copic, Touch, etc) which can also be used for pencils as a solvent blender. There's debate as to how that affects the marker nib... but most nibs are replaceable, so I don't worry about it.
I'm digging back for pictures of how I store my pencil cases and how they 'fit' when I'm working with them... this is what my desk typically looks like when I get going... looks like I had 5 or 6 ideas going at once here! LOL... I miss my desk!!