I solved it.
I am using plugin “Woocommerce Print Invoices & Delivery Notes”
This is a different plugin then “Woocommerce Prin invoices & Packaging Slips”
First you need to get order ID, in my case it was is a URL GET variable.
$order_id = $_GET['order_id'];
After that you can get all order data (array):
$my_order_meta = get_post_custom($order_id);
If you want to see what’s in the array, do a print:
print_r($my_order_meta);
Now you see all fields which are used on the specific post/order. The WCPGSK fields are in there as well. I was looking for a field called ‘billing_leverdag’ which I made myself with WCPGSK.
Now I can easily echo my field:
echo $my_order_meta[_billing_leverdag][0];
After that, offcourse, I commented out my array print which I mentioned before.
I can imagine this solution should be useful for all ‘I want to print custom fields from WCPGSK into [whatever]’
