Based upon my
experience downscaling the
Canon Creative Park harp model to 54%, it's a medium-challenging plan. The designer is K. Yoshinaka/STpers. Built full-size, it would be 1/6 scale, about a foot tall (30 cm). Most of the geometry is reasonable, except for the teeny triangular facets that the plan has on the inside curve of where the top piece meets the diagonal piece—I omitted those bits—and it was tricky to do a clean job with the pedals, at least with the smaller scale that I used. Also it would be nice if the colored-in areas extended a little beyond fold lines as well as into the areas where other parts are anticipated to glue on, so that slight misalignment doesn't result in unprinted white areas showing. Otherwise it's an elegant shape. Note that the strings are not under any significant tension and aren't meant to actually be plucked.
As you can imagine, it doesn't take much tilt for the model to tip over backward, so I'd recommend gluing a thick brass washer or something similarly weighty inside the bottom of the vertical post portion of the model or inside the internal hexagonal support structure underneath the post. I forgot to do that, so instead later in the assembly process I put a couple thin washers inside the base under where the diagonal arm attaches, which was not enough to make it really stable.
If I were to build it full-size to the plan, I'd be tempted to modify the plan so that it has the full complement of 47 strings, rather than the included 17. Adding in-between strings to bring the count to 33 would be relatively straightforward, in terms of keeping the attachment points spaced such that the strings stay parallel, while redesigning with exactly 47 strings would take some layout work. Careful if you try more than double, since the strings would get pretty close together. (One way to make it easier, though inaccurate to the prototype, could be to have the strings come out of both sides of the top piece, rather than just one side as the plans have it.) Also, if you do go for the full set of strings, you've gotta color the C strings red and F strings black. It would look pretty nice!