These are models for various pathlength centerpieces for analytical ultracentrifugation. For the OpenSCAD code please see https://sedfitsedphat.nibib.nih.gov/info-and-tools . The code has some parameters that allow customization, for example of the pathlength and imprinted name, as well as diameter for finetuning of fit into the barrels.  

The model feature embossed gaskets for improved seal and a dome at the sample filling side of the sector to facilitate loading large sample volumes. 

It is highly recommended to print this centerpiece in Microfine Green or similar material with high resolution. When using other material that is not as soft, the embossed gaskets should be removed. The model should be printed with the flat sides at top and bottom.

For more details see https://pubs.acs.org/doi/full/10.1021/acs.analchem.9b00202 and http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0155201.  

For questions and discussion, join the SEDFIT-L list (https://list.nih.gov/cgi-bin/wa.exe?SUBED1=SEDFIT-L&A=1)