If you only have one item per order, then you could record the size and weight in the order table itself, rather than creating a new table [Late edit :, or as you suggested create a table of standard measurements.]
However, there are probably going to be multiple items per order (e.g. 100 of product x and say 1m of product y on the same order) so the readings/defects table should really link to the line item of the order instead of the order itself. To do this you need an order_item table (with a unique id of it's own, which would be the link back to the readings/defects table) plus it would link to the orders table using the order id. This table would contain all of the products for each order. Meanwhile, the order table has the customer details, date etc.
There are a couple of ways of recording the size and weight, depending on whether the products only come in standard sizes and weights, or if they are custom made.
If the products are all standardised (i.e. the customer selects from a pre-defined list of box sizes and the customisation only involves external printing and other cosmetic changes) then you should have a table of products and in there you could record the size and weight for each type of box. The order_items table would link to the products table via a product id and given the readings/defects table is also linked to order_items then you have a link in your data and you can do the standardisation calculation in your query.
However, if the products are highly customised, then you should record the size and weight etc in the order_items table (rather than creating a new product for each and every possible size and weight of box) against the product ordered by the customer, but this would occur in the order_items table, not the order table. This sort of set-up is almost exactly what you proposed in your [Late edit : second to] last post, except I have expanded it to take account of multiple items per order.
HTH, Andrew
[Edit : P.S. It looks like you beat me to it - you answered your own question while I was typing my response (and saying goodnight to my son), but you may still need to look at the multiple items per order scenario
]