Core (Tube) Brush Stand (Hex Drive Type) for 12 Brush Set

I recently bought this core brush set https://www.amazon.co.uk/dp/B0C3HMF846? to clean out the main nut on an engineering vice I've been restoring. They did a great job of clearing muck out of the internal threads, but they just arrive in a bag with no sizes marked on them, and if you touch the wire bristles with your fingers they bite HARD :o)

So I wanted some way of storing them in sequence. I'll mark the shafts anyway, but much nicer to have a labelled storage rack. They go up in just 1mm steps so I had to grab a vernier to arrange them in order!

I sliced the STL and found the layer where the size numbers start, and added a colour change in my printer code for the numbers. Unless you happen to have an Elegoo Neptune3 Pro like mine, the final gcode would be of little use so I haven't included it as the layer number might be different on another type of printer or with a different layer thickness. Alternatively you could print the model in one colour and use a different coloured permanent marker to make the numbers stand out.

To avoid the bottom of the holes having to be drawn on infill, I recommend 4 bottom layers, but check that's correct in your slicer before printing, if there's infill under the holes it's difficult to print a flat bottom for the holes. To make sure the top is nice and flat use 4 top layers too. Infill I just used 10%. 0.2mm layers and a 0.4mm nozzle is fine for this model.

The reviews for the core brushes suggest that they're not up to doing major rust removal sideways-on on the outside of an object, but for their intended purpose of cleaning out a tube or internal thread they certainly did the job for me, just make sure you only run them clockwise (or the twisted wire could unravel and dump the wire bristles), and use approximately the right size for the job as one that's too big could jam.

Hope this stand comes in useful for someone else!

I didn't fillet the model before printing for myself, and finished it with a deburring tool. Before publishing the STL here I filleted all the edges and the tops of the holes, and made the holes a little deeper so that 4 bottom layers should give well supported bottoms to the holes without needing heavy infill. I checked it in my slicer but haven't printed it - please let me know if there are any issues and I'll do my best to correct them!