Android POS application print function

We have built an android POS application and at a stage where we need to print recipes from our newly developed POS application. The POS application will be installed on a POS terminal we have developed in-house. Its an all in one terminal with a 7" tablet/Android 5.0 OS and an OTG USB Thermal 50mm printher. We have installed a universal USB OTG printer driver on the device and have successfully printed a couple of test pages to confirm the communications status between the Tablet and the Thermal printer over OTG. Now we need to install some code to our "Print" buttons in the application to execute the print job and send it to the printer to be printed. So my URGENT request is for some to assist me to code and integrate the code into the Print Buttons function as an action to work and set up the slip layout. The Successful end result should be when I can print a transaction ticket from my POS terminal via my POS application. simple! PLEASE NOTE: My project is due to be delivered tomorrow and I need some urgent to assist me tonight to get this application to print slips, please. Kind Regards , Peter