[funkytim]

Does anyone make any "plywood" that would consist of equal parts stone, plastic, wood and metal?  Seems like a good way to keep mages from casting Shape [material] spells on important doors or walls.  This would probably make the object resistance higher too.  Just a thought.

[Xenon]

Its not really the GMs role to make it impossible for the players to finish the mission. It is not GM vs Players

Having said that, magician can still just project through it.

If you want to make it mage resistant then you would typically use some sort of mana barrier (a ward ritual perhaps).

[Stainless Steel Devil Rat]

Yeah, but sometimes it's the players who are trying to fortify a bolthole or safehouse... and players as a rule don't want to offer the npcs a fair chance

Also, a lot of building techniques already incorporate composite materials: (stone) concrete with metal rebar, a wooden door reinforced with metal, etc.

All that being said: yes, the go-to for astral security concerns is to go with wards.  And if you got more concerns and resources, have a mage keep a low force spirit on watch 24/7.

[autXautY]

I'm not a structural engineer, but I imagine it would be hard to make a really multi-material wall very sturdy. You'd have to be using a lot of non-optimal materials, since using only the one or two "best" materials wouldn't really solve your problem.
You also need to be using a lot of small individual pieces, which means a lot of joins of some sort, and joins tend to be weaker I think? If you use large pieces, a mage could potentially just reshape one single-material chunk
So, there may be a tradeoff between fortifying vs. mages, and fortifying vs. wrecking balls

[Reaver]

Organic matetial alone doesn't keep an astral form out.... its LIVING material that keeps astral forms out...

And its really hard to keep something alive when its wedged into a form fab, and stuck in a living space....

But there options. Awakened Ivy, FAB2 formfactors.... but most of those havn't been seen since 3e

[Typhus]

Watch a video about a remodeling of a room or construction of a high rise.  There's already multiple/hybrid materials in walls.  A spell that's limited to one element probably can't make a hole anyway.  You'd need  a generalized spell that works with any material, using the ORT to determine effects.  Higher drain, but more versatile.  Like the opposite of Strengthen Wall, I would think.

As I recall, the FAB walls and mage ivy don't stop spells, they just made it hard for astral travelers.  It's been many a year since I looked at that sourcebook though.

Another answer is in the "weave" idea, which could weave various materials through or around the primary material, thus increasing the tier of the ORT used, or else disallowing the single element spell from working/working easily.  Is a wood wall infused with a high tech weave still "wood"?

[Xenon]

Organic matetial alone doesn't keep an astral form out.... its LIVING material that keeps astral forms out...

It is typically active MAGIC that keeps astral forms out.
Active magic typically have an actual tangible form on the astral plane.

Living entities on the physical plane typically 'just' have an intangible astral aura on the astral plane that a wholly astral entity can simply pass through without any consideration at all (unless they are dual natured, but in this case they are typically also actively magical in some way).

[Aria]

Did ‘living rock’ used to stop astral entities? I vaguely recall that it did, otherwise how did the ED kaers keep the monsters at bay?! Yes, I know they were warded too…

[MercilessMing]

Does anyone make any "plywood" that would consist of equal parts stone, plastic, wood and metal?  Seems like a good way to keep mages from casting Shape [material] spells on important doors or walls.  This would probably make the object resistance higher too.  Just a thought.

I think it's a good idea.  A material engineered in this way wouldn't need to be equal parts of all those things, it would just need to be not predominantly one of those things.  So you could do it with three.  It's probably not going to have a particularly strong barrier rating, though. 

[Typhus]

Did ‘living rock’ used to stop astral entities?

Where is that from?

[Stainless Steel Devil Rat]

Did ‘living rock’ used to stop astral entities?

Where is that from?

Earlier editions of Shadowrun (1, 2, and iirc 3) had the metaphysics of astral movement where astral forms couldn't move through living auras.  In these older editions, mundane ivy growing on a wall was an effective astral security measure.  You also could not project through the ground, and the term "living rock" is iirc shared with Earthdawn which was Shadowrun's sister game back in FASA days.

At some point since then (IIRC, 4th edition) the lore/metaphysics of astral space was changed and from that point onwards you COULD project through living things.  But, still not the gaiasphere (which is the en vogue term to use now, instead of living rock).

[Typhus]

Ah, now I get you.  Thanks.