Converting Mandrakes to Warp Spiders

I prefer to play doth DE and Eldar rules and mix both armies in my lists, but mu Eldar always look like Dark Kin. So I converted a coven moster as a Wraithknight and so on.
And now I need Warp Spiders. Original models seem to be bulky and not proportional (like most os Eldar infantry models), so I think the best way to represent transdimensional nature of this unit is to take Mandrakes.
But I don't know, how other player will accept this, maybe there will be difficulties to enter the tournaments with some WYSIWYG requrements.
Will it be enought just to equip them with guns like Shredder, or do I need to use more bits?
What are your ideas, maybe you have seen/made similar conversions?

Mandrakes look nothing like Warp Spiders so you're two options are just roll with it and make them look however you like and proxy them (people will either accept them or not) or do some heavy converting to make them look even remotely like the original.

If you want something unique but that can pass for WS's on the table then you'd need to look for something more armoured to begin with. Best I can think of from the DE range are Incubi. Scourge would work but they poses are wrong for blinking troops. Your best alternate chassis would be the new Shadow Spectre aspect warrior. I found these after some googling, looks like somebody else had the same idea to turn them into spiders (they look like better warp spiders than the actual WS models) http://www.dakkadakka.com/dakkaforum/posts/list/652049.page?userfilterid=49729

There are also these here:


Not official, but vastly superior to GW's.