Enter the string value that you want to convert to hex values into the box, and watch the program do its work! (I HIGHLY SUGGEST USING TURBO MODE.) (Also works for converting strings to decimal value, although that usually isn't quite as useful.) As always, this is Scratch; feel free to remix, steal pieces of code, etc. I wrote the custom blocks to be as self-supporting as possible, so there's minimal external setup for what they do.
Kudos to my sister @juliemin888 (fancier account @-FrozenFlame-) for being the Scratch-obsessed person she is, and peer pressuring me into making /something/ on this site that I practically never visit. The purpose of this exercise was to play with Scratch's... interesting shortcomings in variables and type, as well as practice my ability to work with non-strictly-typed variables. Most of my coding experience has been in Java, which is a strictly typed (I think) language, so playing around in Scratch is a very different experience. If you'd like to check the results: http://www.rapidtables.com/convert/number/hex-to-ascii.htm