simple calculation / timer app

I need an Android app. I would like it designed and built. Our company requires an application to be written to calculate the parameters used to weld polyethylene pipe together. The app will incorporate a calculator and timer functions to guide the user through the welding process. Similar apps can already be found on the Play Store and iTunes app store by searching for PlasticWeldCalc or PolyCalc. Colour schemes, logos, artworks, parameters, machine information will be provided by us. To create a mobile application for both iPhone and Android based on a relatively simple calculation formula. Maximum of 6 numerical inputs are required, using predetermined values from drop down menus for all but one of them. The output then steps the user through a maximum of 6 stages of operation, presenting calculated values, and requiring confirmation before proceeding to the next. Two of the outputs in the form of countdown timers then result in an alarm at the end of each section of the operation. This is a quite simple App, but the visual must be excellent, simple yet inviting, and in full compliance with our corporate image. I am no expert, but I get the impression that good graphics will win this. The back-end is not rocket science. One of our people had that almost done within 24 hours, but making it look good and be easy to use for people who usually don't use Apps is what we need. Users will be contractors, miners, labourers. When you apply, send me examples of your work.