Custom G-code at end of prints?

[Vogelindustries]

Can custom G-code be added to the end of prints? On my FDM printer I use the code below to beep 3 times to let me know a prints finished. 
Also thinking about adding some kind of Z shake routine at the end of prints to get some resin drips off. would that be possible?

Code:

;Beep Beep Beep
M300 S500 P250
M300 S0 P500
M300 S500 P250
M300 S0 P500
M300 S500 P250
M300 S0 P500

[Roman Kornfeld]

In Chitubox App in Windows there is a ELEGOO_MARS.cfg File for the Mars.
There is a Option for Custom gcode. 

gcodeEditVisible:1

Set it form 0 to 1
then add a new elegoo mars Printer in Chitubox Setting
Then you have new tab with start and endscript.