I want to create purchase order on behalf of customer

I have a factory in which i’ll be manufacturing the t-shirt. The customer gave me a purchase order of t-shirts of black and white color. And both t-shirts have 4 sizes.
M, L, XL, XXL.
So i created the Template of the item. As i will be manufacturing these items, what all things should i select in item master?
Because when i created a purchase order of these products, i got this error,
Following items T-Shirt-BLA-L, T-Shirt-BLA-M, T-Shirt-BLA-XL, T-Shirt-BLA-XXL, T-Shirt-WHI-L, T-Shirt-WHI-M, T-Shirt-WHI-XL, T-Shirt-WHI-XXL are not marked as purchase item. You can enable them as purchase item from its Item master.

Why do i have to select is purchase item check box? And also i have selected material request type as Manufacture. Please explain?

As you are selling these items. You have to create a Sales Order.

From the customer’s perspective its a Purchase Order
but from manufacturer or seller’s perspective its a Sales Order

But what if i want to create purchase order for customer, manufacturing process and sales order. All three things?

You could create another document type which you have filled on the click of a button; or even only a report template: which takes the data from the Sales Order you create for your archive/side of the deal, and then prints it as a Purchase Order from the perspective of the Customer, e.g. reversing Addresses on the template, maybe change the legal texts (?) if need is, and what else needs to be adapted.
The manufacturing process is probably initiated by yourself after receiving the order from the client, so why would any change be needed in there?

Hi:

Create sales order for customer. From this you can launch all the following business processes:

image

Maybe material request, and from here purcharse order for raw materials, work order for manufacturing, etc … All the documents will be connected.

There would be many variants …
Hope this helps.