I often do stand or semi-stand developing of my large format negatives in a Paterson tank. As the tank I use is made for one 120-film or two 135-films I simply insert the film sheet in the tank with the 120-spiral taken out. This resembles the so called taco method but without the hair bands. It works, but at the rate of one sheet per go it is time consuming.
Still without hair bands I decided to have a go at making an insert for, at least two sheets, with an expected 200 percent increase in throughput.
Starting off with two blanks of perspex plastic, a hole was drilled in them to make a tight fit over a centre post found elsewhere. These blanks were quite thick, some 5 mm. A first version was made in thinner, circa 2 mm thick perspex but the film was very flimsy in these. So a thicker slab was tried (and gave me a chance to take photos of the progress in the shop).
Their size was determined by the Paterson tank. Corners were cut to fit (I always try to cut corners, haha!). Note that the tank gets narrower towards the bottom.
One of the two finished holders. For the sheet to really stay put, these long cuts were necessary. Without them the film would easily jump out of position.
Now if two sheets fit that well, how about three, or even four…?
I admit it is not a beauty, but it works!
With a squeeze even a fourth sheet will fit. This sheet will need a rubber band around it and the centre post as it otherwise will jump out of position immediately! The others will stay in place due to the springiness of the sheet film.
I then fixated the two holders onto the centre post with the help of a glue gun. If you have not tried a glue gun yet, get one! It is a truly remarkably useful tool for almost anything.
This far I have only used it for developing two sheets at a time. It is somewhat tricky to get the sheets in place in complete darkness but if you are not in a rush it is quite doable.