Small screw top containers with multi start threads. Note that these are very non-standard threads. There are two sizes and a couple of cap variations. Another variation is that the smaller container has more and smaller-section threads which I think are a little easier to print.Made in Diamond Age PLA on an Ultimaker. 0.2mm layer height, 200C. The cap is neat fit to the container which is good in some ways but does mean the the cap and container need to be 'run in'. Clean the threads as best you can and then 'force' the cap onto the container. Generally I found that I had to hold at least one component with a tool (Jar opener or multi grips) sometimes both. Then work them to and fro a dozen times and all should be well. The result should be a snug fitting lid with little play or slop.