This is a revision of the media adapter boards I've posted--a variation of this one for instance: https://www.pcbway.com/project/shareproject/BNC_to_Banana_x3_adapter_board_fce9876d.html

It's three PCB mounted BNC jacks (my function generators and scopes use BNC); each BNC goes to to dual 3.5mm female jacks--since, as a synth/audio guy, a lot of what is on my bench under test has at least a few 3.5mm jacks.

Typical use case: I was finding I was often mult-ing the 3.5mm jacks on my bench, sending one signal to a preamp so I could hear it, and another to the project on my bench. I was doing this to A-B the source and output for (say) audio filter development.

But I also wanted to see the signal on my scope. Hence this PCB.

The board has 3 sets of BNC --> dual 3.5mm on a <100x100mm 2 sided PCB.

The jacks used are Switchcraft 35RAPC2AV jacks for 3.5mm: Digikey SC1457-ND. 

The BNC's are SuperBAT clones of (very expensive) Amphenol BNC's, the BNC clones are available at Amazon--search for these--Superbat BNC Connector BNC Female Bulkhead Solder PCB Mount Right Angle

Note: The 3.5mm pairs are configured as passive mults. So: you can't mix signals coming into the jacks.