Tinted canopy and cutting into finecast

So I'm new to custom work and never really worked much with painting until recently and I'm looking for any advice you can give.

Yesterday I was looking at the canopy of my razorwing and venoms and started to think they were a little blah, I was wondering if there was a way to get a stained glass effect on them? My first thought was using the glazes or shades GW has since they're basically see through if there's no layers under them, but any alternatives are appreciated.

Last week my friends got me a gag gift of a tau battlesuit commander and two more battlesuits for bodyguards (why I have no idea) but last night I had the thought "Why not make them coven commanded?" and set about making what I'm calling Dark Eldar battlesuits. My plan is to add DE bits here and there, so far this is how it's come...



The two hand pieces I plan on putting the bottom half of that pike on the other side of the hand and adding another sharp piece on the bottom to get the double ended look and the chain piece im planning on taking a longer length of chain and running it from the bottom of the hand into the slot on the arm usually used for mounting battlesuit weapons so it looks like there's more stored in the arm.

My main problem is I also want it to look like the suits were blasted and cut into to pull out the pilots, but I've never done anything other than putting my army together by the book. Can anyone give me some tips on how to go about making the blaster holes and Talos sickle cuts?

That looks really cool. Make slaves of the Tau!

Honestly, with the way the Coven supplement reads we can bring haemonculus back to life, so why not animate Tau corpses and modify their armaments for reusable fodder. That's what my coven Pestis (meaning: pest, pestilence, Plague, bane, disease, and death) does best, though they may be missing limbs and have weapons in their place.

I've already got most of what I have for Tau done including a little joke squad of fire warriors posed like dancers in the Thriller video, once I get my camera working again I'll post pictures of everything over in the project logs.

You have to heavily modify them! I've got an idea, make the armor torn open on some spots and those openings covered with Flesh and parasites. Some brain parasites like Medusa perhaps.

That they got infected by some Haemonculus thing that turned them into grotesques. That are still in their suits!

I'd love to do something like that but I have some problems
1: Since my Dark Eldar army had to get put together in a couple days for a tournament I was going to, one of my friends did it so they'd be done in time so I'm new to modeling and these are the first ones I'm actually doing my self.
2: How, that's kind of the point of this thread is saying I have no idea how to do custom stuff, even what I have done is very basic. If you know where tutorials that are actually informative are or have tips of your own please tell me.
3: I have tremors bad enough that I try not to use knives if I can help it especially if I don't know what I'm doing.

On a side note, of the suits I have the commander will probably be the heaviest modified out of them, sort of a he was the first to be modified and through him we know how to blend in more as Tau. After all if you can use a few expendable soldiers to trick two factions like the Tau and humans into fighting each other, why alter your toys to no longer look the part of this deception?