It's awesome, I'll suggest something but I feel it is very hard to do it.

My suggestion is that you will divide that line of TNT using pistons into diffrent parts, each way will have a different texture using colored BIZRand finally, use pistons to merge those different parts into maybe 32x32 or 16x16 px square.

You can make any cuntom texture, maybe even use minecrafts TNT texture if you want oh and make sure that you only spark that button once to create one TNT block. Believe me, thats 100% possible but it's hard, if you made it, then I'm sure you will get to the FP and be in the first or second or third place and will stay there for 1 week.

That's really good, the only possible problem is the 'retrieve' button. Guess you forgot PSTN can only push 29 pixels of FRME. You could expand it by making more than one factory and pushing all of it into one line. @Protcom 's idea sounds possible, but ridiculously hard. You could try it...