Optimization for Steel Cutting Linear 1D cutting optimization

We have a list of steel sections with profile. excel of which is attached in this project. We have various lengths of steel sections. We need to find optimum source (stock) steel length with maximum 3 different sizes (e.g. 50% to be 2.5m, 25% to be 3.00m and remaining 25% to be 3.55m), not exceeding 3.7m in length.

As we have the option to produce custom source (stock) steel section length. I need the optimum solutions for the same to find the cost effective solution and optimization. As we need to order the steel materials in optimal length as soon as possible.

There are 6 types of steel sections:

RHS 100x60x2.5mm

RHS 100x60x3mm

RHS 120x60x3mm

RHS 120x80x4mm

RHS 120x80x6mm

RHS 80x40x2.5mm

The requirement of each are given in the excel attached, we need the optimal length of the given sections with respect to the excel quantity requirements for procuring the materials.

Please get back to me for any further clarification.