I want to improve in general, and explore a few other scripts to find what works best for my hands/brain. So I don't need to make a convincing Spencerian forgery, just consistent, readable, and neat cursive.
The slant rule paper came from https://www.amazon.com/dp/1794289798?psc=1&ref=ppx_yo2ov_dt_b_product_details
But if you're just going to copy it, there's a free course at https://consistentcursive.com/ that includes a printable worksheet that has the connective and main slants instead of the 45 degree rule the product above has.