I have always done it by hand too. In all seriousness, I had to weigh each item and then manually enter the weight into the invoice. I was helped by my smart scales, which were very accurate. I got this scale from https://www.vont.com/product/smart-scale-bathroom-scale-weight-scale/ to keep track of my weight, but they turned out to be very versatile, and I use them at work. I hope that I will also soon have an automatic calculation of the weight in the invoice, and I will still use the scales for their intended purpose.
I have always done it by hand too. In all seriousness, I had to weigh each item and then manually enter the weight into the invoice. I was helped by my smart scales, which were very accurate. I got this scale from https://www.vont.com/product/smart-scale-bathroom-scale-weight-scale/ to keep track of my weight, but they turned out to be very versatile, and I use them at work. I hope that I will also soon have an automatic calculation of the weight in the invoice, and I will still use the scales for their intended purpose.