Reverse Charge under GST in Scrap Trading Business

I trade in all kinds of Scrap like Plastic,Iron,Books,Steel etc.

I purchase scrap from local cycle vendors or from household Scrap they are not registered under GST regime.

My total purchase per day is Rs.15000 to 30000 daily. I made sales to big industries were I get the Tax and I paid to the government. .

So my Question is. How to record Purchase ?

Right now I am just writing down my purchases in register without raising any bills/Document.

GST rate is 18%. On iron and 5% on books.. how to make Bills on reverse Charge..

Can I make one consolidated bill at the end of the day/week??

But how can I make a consolidated bill when GST rate is different in different items? Please suggest me some advice.