Looking back over the development of this device I feel I may have become a little guilty of taking a simple concept and making it complicated, but with good intentions. This design has been 100% built and tested, and whilst I call this the Mk3 design, I've actually made and rejected about 6 other design iterations that haven't made it to public viewing. Each released iteration of this design I feel has some merit and maybe drawbacks ,the first benefits from its pure simplicity and is very strong, the second benefits from being made without need for any hardware, and this version....? I suggest to those interested, that rather than just opt for the latest and greatest option, you consider the original or Mk2 as viable alternatives... maybe even remix elements of the three designs to make something that better suits your needs. What I've added to this version is a spring loaded universal spigot that is adaptable to any size central hole, the first two versions solved this problem by using the spigot inserts, and if you rarely change your brand of filament then this is simple and great, but each time you try new filament you may need to first make a new spigot adapter. This design does require a little hardware for the spigot assembly, namely 2 elastic bands and 3 10mm M3 countersunk screws, hence the loss of its 100% poly rating. With this iteration I think there is still room for improvement and I offer the challenge to improve it to others, Whilst I would particularly like to get rid of the screws and the elastic bands my attempts at doing this yielded poor results, maybe find a better way of setting the spool in place, or making the assembly a little easier, there is a lot of scope where an imaginative builder can effect improvements, but for myself I feel its time to move back to my other projects. BTW apologies for the poor videos, they are there to try and help, but you may enjoy them for their comedic value.... pity they don't do Oscars for best movie where the camera falls over. https://youtu.be/V1y7jMeg4qU https://youtu.be/bnAwEl8AEoA There are a total of 19 printed parts in this build, 12 rollers, 3 arms and the 4 disc parts, all are printable without support. 0.2mm print height is recommended, particularly on the main discs with clips or bearing surfaces. all parts on my prototype were printed in PLA on a RRP Mendel 3 with a 0.5mm nozzzle If a higher load capacity is needed you can make this without a spacer plate, just print a lot more rollers and fill the race with them. When printing the rollers its best to print them with the large end on the bed. Its best to assemble this from the top down clip the cam plate to the top race with the arms between them and the pins in the outter slots, this may be a little tricky, but take care to not break the clips, it may help to use the blade of an exacto knife to carefully lever the clips open. Next insert three M3 countersink screws, making sure that the arms can move freely and the screws don't protrude from the bottom of the top race. The screws should self tap into the plastic, but may benefit from running a 2.5mm drill through the top race holes and a 3mm drill through the arm holes, if you haev a M3 tap then use this but its not essential. Next attach three elastic bands and check that the arms spring outwards and when you pinch a pair of levers at the edge the arms should contract, try fitting it to a filament spool. Before assembling the races first check that the rollers will roll free in each of the races, if there are any bumps of irregularities trim with an exacto knife.