Original image

step 1 of 8
Any color will do... I choose light blue since it is simple yet nice to look at... Plus with this setup, it's less distracting...

step 2 of 8
It doesn't matter in which order you trace the part, but it's advisable to start with front object and then to back object( bottom to top)...
Also I named the layer properly... It's better to name it carefully...
Otherwise it's hard to arrange layer when they are named layer 1, layer 2, layer 3, etc... In this case there are lots a layer in the end...

step 3 of 8
As you can notice there are some white part at the speaker's border... Now we don't need that... So I painted black over it...

step 4 of 8
Also while converting the path to a selection, I choose feather of 0 px, since I want the edges to be sharp...

step 5 of 8
I have marked in the ss which parts I have broken...
Also I group all this objects into a layer group conveniently named "Left speaker area"...

step 6 of 8
So in this way I traced the other section of the tape recorder as well...

step 7 of 8
My arrangement is as show in the figure, cause I want both of the speaker section to come out above the middle section i.e. the place where the cassette goes in...

step 8 of 8
One can arrange it as he/she wishes... And I didn't add any insides, cause I didn't want it to be real or realistic or a blueprint type...
Just was having fun with the image or so to say the lineart...

Final result

