The shape for easing the finger joints is easily draw by positioning some circles (it may be easier to temporarily turn off the fillets) and then drawing rectangles which snap to nodes and halving their sizes to make them fit:

As has been noted before, while one could just Boolean union this, that results in a polyline with a lot of additional nodes which make snapping error-prone. Best to re-draw the shape with the curve tool.

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Re-drawing is pretty straight-forward:

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Duplicate and flip and drag the duplicates into position:

And add a series of rounded rectangles which one can use with toolpaths to trim the boards to length:

The pocket geometry should be duplicated and the dupes Boolean Unioned for the initial cut to the pocket depth, then the afore-mentioned rounded rectangles can be used for the through cut.

The whole thing will probably be easier to envision (and to cut) if we space out the boards and add temporary for preview only toolpaths to give the monolithic stock the appearance of individual boards:

Next draw in geometry to relieve the opposite set of fingers and make a suitable through cut:

resulting in:

Lastly, duplicate all the geometry and toolpaths to cut joints in the boards at each end, name things appropriately, and set the spacing of the parts and toolpaths to make setup and clamping as straight-forward as possible.

I’m confused on what bit you used on these fingers, because the simulation has contours that suggest a radiused bit or a V-bit.

Correct, the fingers are relieved with a V carving (need to look into getting a suitable radius endmill) so that the box can be cut with a single setup — read the entire thread for all the gory details.

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Looks like this radiused endmill may work:

https://www.amazon.com/Micro-100-CRE-312-125-Rounding-Diameter/dp/B00Q8M1SRS

but I’ll need to get a new collet — guess I should lay in a stock of all the sizes.

For the boards which need through cuts, draw in geometry:

and Boolean union them.

With appropriate toolpaths and names we make:

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I like this idea because I’m sure that most box joints I see use way to many fingers. These boxes don’t need so many fingers to hold them together. +1

Next up is trying to model and create toolpaths for a radius endmill to do the relief.

First we need a half-profile of the endmill:

Once we have that we render it as a polygon in OpenSCAD:

then rotate extrude it:

which will allow us to use it as a tool.

I noticed that the box tool you mentioned earlier (makercase) now will do cut compensation specifically for routers, given the size of the bit you wish to use, making all the handling post download unnecessary.

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Yes, but the compensation in that program seems to result in voids.

Dogbone cutouts are very much a matter of personal taste, ranging from “I like them” through “eh?” to “that’s a special kind of ugly”

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The cutting worked out pretty well:

and now that I think about it, can get the correct angle on each front/back piece by just re-orienting them — will have to build that into the system.

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A variation using a radius cut and a V endmill for relief:

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