Create images for buttons within my application visualizing moving through phases

In my application the user can take an object through various phases in a “life-cycle”. I have created 3 images to give an idea, but would like more professional looking versions. 1. Move to the next phase in the life-cycle 2. Move to the previous phase in the life-cycle 3. Move to the final phase in the life-cycle The images should have the same size as the samples I have attached. Desired format is either png or wmf/emf, where one should take into consideration that when deliverd in png, it should be possible to convert the image into gif-format without decreasing in quality.