If you have a pricing formula, part formula, or weight formula that will repeat throughout several products, you might be interested in using the "Proxy Variables" - sometimes also referred to as "global" variables.
This proxy page will allow you to create a formula and give it a name. For example something like this:
You'll see the "Variable Name" at the top has been titled Door_material_cost.
Once you've created and named this formula in the proxy section, you can then go to a product and use this new variable in your formulas!
So in this case you'd now go to a product and see Door_material_cost as a new variable available in the side bar. Using this variable effectively plugs in the entire formula you built in the proxy section:
You can combine more calculations along with that variable as well.
e.g.
proxyvar.Door_material_cost + ((21.99 + (parts.panel.Qty * door_style.extra_panel_cost) + hinge_drilling.price)
One thing to note as you're building each of the proxy formulas you'd like to use - there is no form of validation or checking for errors on the proxy page. This means you could accidentally mistype a variable or forget a parenthesis and you wouldn't realize it until you'd added the proxy variable to a product and realize it's not calculating quite right.
To avoid this issue, we recommend you FIRST build the formula in one product. Because on the product you have access to all the variables you need, and you'll be warned if the formula is broken in some way. THEN once you've built it there just go create a new proxy variable and paste it there. At that point you have your new pretty proxy variable to go use on all your other products as needed!
Once you're ready, the way to get to your proxy formula variables section is under the main nav settings icon: 
On that page it will look like this (if you have no proxy formulas built yet), and you can starting adding new ones by using the "Add New" button in the side bar:
