First of all you will need either two IDC20 or IDC26 female connectors and one IDC50 female connector. They all have 2.54mm pitch and can be easily purchased on eBay.

IDC20 (SASI)	IDC26 (SCSI)	IDC50 (Common)

Next you will need a 50 way AWG28 colorful flat ribbon cable with 2.54mm pitch and a IDC crimping tool.

50 Way Cable	IDC Crimping tool

This is how an original SASI cable looks like. It is approximately 34cm (13.4 in) long.

Now use the following pinouts to align the cable with the connectors. Click on the images to enlarge.

SASI pinouts	SCSI pinouts

Once alligned, it should look similar to this. (a completely unrelated IDC connector is used in the following example)

Now use the crimping tool to finish the job.