Problems with shipping algorithm

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My problem is with different types of products. Some products weigh about 25 lbs. Some weigh less than a pound. Different shipping algorithms cannot be applied to different products. I either lose money on shipping or charge too much. Is there any solution?

https://www.drct.com/nuclear/index.p...products_id=70
For something lightweight, there is a flatmate, and it doesn't go up much with multiple units...but the current shipping algorithm makes the price go sky high. If I base the shipping on actual weight, I lose money.

For heavier items, the shipping algorithm works quite well.
https://www.drct.com/nuclear/index.p...index&cPath=10

Not sure what the solution is. Any suggestions?