This turn of the century style of roundhouse/enginehouse is nearly impossible to find. I had to have it in spite of its original list price. It is billed as an HOn3/HO model. The only way this kit might fit an HO engine is if code 70 track or less is used (I used code 83) and the ties are removed within the building. The laser cut parts are easy to remove from the forms. Unfortunately, many of the parts were absent from my kit but Bill Banta was very cooperative in resupplying and advice. The directions are in need of revision to reflect the evolutionary changes made to the kit. Otherwise the kit was not as dauntingly difficult to build as I had feared. Hanging the bay doors with the wimpy, fragile hinges was a no go. I had to improvise with rod stock to retain the open/close feature. I still have to remove those ties and hope my engine fits but even if it doesn't the model will look terrific on my layout. Rolling stock fits.