In this scenario we will have a box that can only take a maximum weight of 35lbs. If items are placed in the cart that total over 35lbs they will be split and multiple boxes used. This will apply to all products for the website.
If its for all products then one way is to set the maximum package weight on the FedEx carrier to 35lbs, currently it will be 150lbs. If maybe in the future you want to have more dimensional rules/boxes then look at solution 2.
- Ensure Dimensional Shipping is enabled under Account Settings->Features
- Navigate to box definitions and Add a new box
- Add the box as below, and within the Basic tab set the maximum weight you want in the box