I know in the old days that it wasn't an issue but now and in the future we are living in a sue happy world . And no disclaimers or waivers are good enough to protect you from a vigarous lawer . If you are going to build a vehicle of any kind for someone else , you are putting yourself at risk , if a collision or a stucture failure should happen . Even if they can't win a case they can eat up any pofits you make and more in the fight .