What rockwell doesn't give you with their model is a way to secure the work against the table so that it isn't jumping up at your face and hands constantly.
I'm still gathering parts to create something similar to a rockwell bladerunner for some small parts work out of a Harbor Freight jigsaw.
I will mount it underneath the table and use a zero tolerance insert to keep work from being sucked down by the blade, and mount a clear acrylic tube over top the blade that I can push down on the workpiece in order to see the line I am cutting and keep the workpiece against the table. The tube will also provide vacuum clearing of the dust and chips from above.
I will use a REVERSE CUT blade in the jigsaw so that when it is mounted upside down, the saw will cut while being pulled back down towards the table, rather than trying to cut on an up-stroke. This will also mean that the force being used to keep the work on the table doesn't have to be extreme, and I will have the necessary play to move the piece around as I desire.
When working with home-made tools, keep in mind that your safety is your concern. If you don't make it a high priority, you have only yourself to blame for any injury caused to yourself, your property, and your friends or family, if there are any accidents.
I blame rockwell for not properly providing appropriate documentation and attachments for their tool to prevent accidental misuse or improper use as well as their failure to plan for appropriate safety equipment that should have been built into their design.
The fact that they don't even supply the appropriate type and style of cutting blades to use their tool safely is beyond negligent. (reverse cut)