Back in the early 1990's when I was a local newspaper photojournalist, I had a wonderful Tokina 80-200mm f2.8 with one problem- it didn't focus closer than two meters. My local Ritz camera has a set of A series extension tubes, 13, 21 and 31mm. I bought them and always carried the 13mm and 21mm tubes. I used the 13mm to make my telephotos focus on close subjects and the two tube together made my 50mm lens focus to hold life size or so. Jessop made the tubes and they are VERY much worth with finding.
ANYHOW- I decided to try my Plastic Fantastic with the 21mm tube. The quick test shots taken with my tripod mounted K-70 using the 2 second timer/mirror up and live view are attached. Files were not cropped and only slight exposure adjustments. All I can say is- I don't think I need to buy the Limited 35mm macro.
Tubes reviews Here
https://www.pentaxforums.com/accessoryreviews/jessops-auto-extension-tubes-pk.html