Low density air-pistol safety backstop?

It is winter.  Inside practice with air-pistol will go some distance as a substitute for outside practice.  Have hall long enough to have an inside air-pistol range.  Metal, fold-up stand to hold a real trap (good enough for 22 even) can be placed in front of a door at right height.  Wish to have a safety backstop between the trap and door - possibly attached to the door - so that errant pellets do not injure the door.  0.25 inch plywood could work, but something less dense is desirable (lighter than a 3 foot wide piece of 0.25 inch plywood).
Ideas and experiential stories are solicited.  What might exist for this purpose that is less dense than 0.25 inch plywood?  Thanks, Mac

A lot of air rifle ranges use screens such as this one offered by Creedmore Sports: 

https://www.creedmoorsports.com/product/SINGLE-PORTABLE-AIR-GUN-RANGE/Portable-Air-Gun-Range

Get a large doorway entry carpe, the kind with a rubberized bottom and hasn't it behind your pellet catcher.  Can be taken down and stored after shooting.

Lexan works great.

Great idea - sheets of Lexan exist.  Do pellets simply crush themselves or is bouncing an issue?  Thickness?  

Thought of carpet.  Might be too absorbent of lead.  Should be tried.    Thanks to you both.

Just about any fabric will stop, or slow enough to prevent damage, an occasional errant target velocity pellet. Even a few layers of cardboard will work. 

If it happens frequently, especially hitting in the same area, then you'll want something with more strength.

Mac, what I use is a sheet of half inch Homosote, a pressed paper fibre product, sometimes used for sound insulation.  Should be available at a building supply place.  It retains the errant pellet whole, no ricochet or bounce, no smattering.  Much lighter than a corresponding size piece of plywood.

Dear Ed:   Will look for the stuff.  It is a big help knowing that someone has actually used it as a safety backstop.
Polycarbonate - Lexan would certainly work, but is rather expensive even in 0.093" thickness (about 0.6 pounds per square-foot).  Have plastic hooks that are intended to go over a door from which carpet (or the like) could be hung.  But a self supporting, not-too-expensive sheet would be most easy to deal with.
Thanks.  Mac

Your wife's favorite sweater. Your guaranteed to never miss again! Happy New Year to All!

Company in (sigh) NJ has been in business for over 100 years.  [Note spelling]  However, out here in fly-over-country it is not well known.
Home Depot has something it calls "Sound Barrier Sheathing" that seems to be equivalent.  A 0.5" x 4' X 8' sheet is about $29 and weighs over 30 pounds.  Need a trip to store to look at item.  
Thanks for ideas.  Others here must have dealt with this issue.  What are your experiences?
. . .  and welcome to Ed333.      Mac

I staple a wine box to the back fence, then staple the target on it. Yep, just one of those common 5L wine box, just pull the plastic bladder out of it. my fence is 25 yards from my patio table, I use the B16 25yard slow fire target to mimic Bullseye shooting.

The pellets from my IZH47 go though the first cardboard, and bounce off the back cardboard, and collect at the bottom. You could do the same indoors, but would put any kind of board behind it for safety, maybe a cheap nylon cutting board. You could also put junk mail, or catalogs in the box to catch the pellets.

You won't have to sweep the pellets off the floor either.

https://www.amazon.com/Gardner-Bender-DS-530-Duct-Seal/dp/B000VZPWZW/ref=sr_1_3?ie=UTF8&qid=1483248734&sr=8-3&keywords=duct+seal

get some of this and spread it about 1/2" thick over a piece of 1/4 or 1/2" plywood about a foot square.  never dries, work great, and mutes the SMACK. you won't need the trap, just pin a target to it.

I made a frame from 1/2" PVC to hold mine.

I shoot my air pistol in the living room, at 10 m. JI use an air Venturi pallet trap, with the thick putty backing.   Works super, although my wife's lady friends think one of us is pretty weird (either me for doing it, or her for letting me). I shoot a singlestroke pneumatic, FWB 103, so relatively low velocity.

http://www.pyramydair.com/s/a/Air_Venturi_A_G_E_Quiet_Pellet_Trap_Incl_Ballistic_Putty/1018

Thanks for the suggestions.  More are welcome.  I have a good supply of Duct Seal - the putty mentioned.  Great stuff.
The wooden-box, shallow, trap has been considered [coated inside with Duct seal and with a thin steel plate].  For the same sort of money, and with a similar weight, one can have a steel trap that can not splinter and needs even less maintenance.  In our case, I have had a steel trap for a long time that has been used outside with 22LR.  
We now have a portable stand that looks somewhat like a music-stand, but is more stout and has a top that can be adjusted to be horizontal.  The stand's height can be adjusted so that the trap that it holds is at a normal height.  For a safety backing, we found an rubber-like exercise mat that is large enough to cover the door that is behind the trap.  Errant pellets at target-shooting velocity should not penetrate the mat and we think we have a scheme such that the mat can be left hanging on the door (to utility room).  As with everything bullseye related, this is just the first iteration. When finished, I will report with more details and perhaps even a picture or two.

I use a 22 trap also. To reduce fragments/debris in front of the trap area I fabricate a cardboard face for the trap. Cut the cardboard to the width of the inside of the trap, tape the bottom to the bottom slat, then fold up and tape to the opening. This way you can pick up the trap, tilt it back and all the fragments go into the trap. I save my lead to give to friends who cast bullets.

Edit: Get a light meter app for a smart phone and check that your lighting at the shooter's stand and at the target is above 1500 lux. The international rules have lighting requirements for competition.

Sa-Tevp:   Excellent idea!   I shall do just that.  When used outdoors, one does not notice the ejecta.  Indoors, I too wish to keep it contained.
Will cut a bunch of cardboard in advance once I have the "pat."
Thanks.

The ISSF rule book is pretty comprehensive on range setup. Target height, lighting, shooting stands, etc.

http://www.issf-sports.org/documents/rules/2017/20161213_Rules2017_GTR_Rifle_Pistol_Shotgun_Running_Target.pdf

I don't see anything about lighting requirements for my air pistol. Is there a special section for dots?

Funny guy. Raise you two 5 shot magazines and a bullseye range command phone app:



Of course some joker with one of those CO2 revolvers will come along and call us both gwendolynns...