Telescopic Mechanism for A Lighting High Mast

I need help in designing a telescopic highmast mechanism.I have a slight idea of how it should be but need some guidance:-The system should be motarized,have pulleys,wireropes,roller wheels and limit switches.The pattern design for developing the sheets,I have developed,the mast will be octagonal & dodecagon in shape.The overall weight of the telescoping mast trunks ranges from 250-500kg.The mast will be made of Mild steel sheets 3&4mm thickness.The telescoping trunks are intended to achieve a height of 20 & 30mtr respectively since they are to be used for lighting large areas.Looking forward to hearing from you.