Unfortunately , this solution has a very low resistance (PLASTIC TROLLEY ) and requires additional work because THERE ARE many pieces to BE assembleD , screws ... ETC
WITH the second solution , it can be seen that the carriage is made in a single block and is in the cubic surfaces that open ball bushings which allow the translation of the carriage on the chassis insert.
The advantages of this solution is that the rooms are very inexpensive as the ball bushes . The camera support is very easy to implement and can be done under the conditions and the time given because the chassis is designed as a single unit . The chassis is made of aluminum , which makes it rather lightweight chassis but also durable.
Then drawbacks there ' has not much but you can take into account that the linear ball bearings do not allow a perfect translation and without friction.