This is a case for the FG085 miniDDS function generator made by JYE Tech and sold through a number of different channels. See http://www.jyetech.com/Products/085/e08503K.php for a description.
The case is for the "panelled" version, which contains a nicely made and labelled front panel, but nothing for the sides, top nor bottom. This design does not use the supplied rear panel.
Note that this case is made for the current panels, with a small angle in the sides. Early panels had straight side edges, and I am not sure if these will fit. Also, note there are other cases for FG085 on Thingiverse.
As for the FG085 signal generator unit itself, it should be said that it has many features, and is quite intuitive to operate. The output signal is useful for many purposes, but it is in no way perfect. Considering the cost of the unit, it is acceptable, I'd say. One issue is that there is a rather signficant jitter on the duty cycle for non-sine waveforms. There is also quite a bit of hf noise on the sinewave. Since there is no proper attenuator, low amplitude signals are really not that great, and you should probably use an external attenuator for that.
Should build without support. Since the walls are quite thick, it makes sense to build with thin shell thickness (e.g. 0.7mm) and low infill ratio (e.g. 15%). The case will still be strong.