I'm not sure what the ISOMAC refers to, but I encountered the same problem. I measured and then drew a diagram of the box I desired and then took it to a glass cutting shop and had them cut it out of plexi-glass (1/4" thick). I then used a weather sealant (commonly used for windows) to glue the box together (can also use aquarium sealant). I left the bottom of the box open so I can place/remove the box easily, because the computer heats up fast. I also left a little slit in the top back panel of the box that I can cover/uncover easily with a strip of plexi-glass. This also lets the fan on the computer breathe a little bit better. The whole project cost around $60-$70. good luck

Check out

http://www.raxxess.com/product.asp?ID=548

It's an isolation box made for your computer's exact dimensions. It boasts somewhere around 20db of attenuation in fan noise, and it allows your computer to stay nice and cool through some type of ventilation. I don't know the exact price, but even at a few hundred dollars it's well worth it.

Make sure, whatever you decide on, to not restrict the air flow of your Mac. It's a great way to destroy your computer. If your machine is getting hotter than normal because you've contained it in something, it's a very, very, very, very, bad thing! I worked eight years in avionics/component repair with the US Air Force, and I do know what I'm talking about. By the way, $70 or $80 for a bunch of plexiglass will eventually become several hundred dollars in repairs, or even worse. My advice would be to not do it, and if you have done it, make it right before the death of your beloved machine.

I believe that Iso is worth around a grand.

I have the same problem, one I've been toying with for a year now.

When I had one machine (PC, server sized) i actually built a method of soundproofing into the case. I switched out all the case and CPU fans for quieter versions (which are being made plentiful right now as many people have this problem). I also replaced the heatsinks on a dual processor with more effiecent copper units that let me run fans at a slower speed.

For the inner case I used a thin 1/4" foam, topped by an industrial vinyl product and topped again with a 1/2" to 1" absorptive foam (as space would allow). I ducted the fan outlets with dryer vents and in the end I had an incredibly quiet and cool running machine.

Over time I've acquired a small network of machines including rackmounts, KVM and network switches, UPS power supplies and all the associated cabling. Now I have to build a large cabinet to house all the machinery.

Three things to keep in mind if you build something.

1. Keep it large enough to expand. You may purchase another computer to assist in processing (like VST link) or the next generation Mac may be a different dimension than the current one.

2. Minimize vibration. You can keep that noise from the disk drives and fans from picking up in your enclosure by creating your own feet to set the machine on. You can also buy rubber fan mounts, etc, but if it is in an enclosure it's not as critical. Using the principles applied to commercial barrier products you can coat the inside of the assembly in a similar fashion. A heavy vinyl will keep the inner sound from escaping through the walls of the case, but if you use a thin layer of foam between it and the case you will have an effective absorber as well. Also, a layer of foam on the inside will help absorb the ambient noise from the machines in the case. As long as you seal all openings (cabes, doors, etc) it will be silent.

3. Ventilation. If you can monitor the temp in the cage, all the better. I'd use an active fan of some kind. You probably need a good size fan to move air through the enclosure, not a small 80mm computer fan. On the exhaust you can essentially build yourself a muffler and attenuate the the sound escaping through the vent considerably. Provided you have a sufficient enough fan, you can have it exhaust into an area at the top inside of the case that would be equal in height to that of the fan casing. You could tune the casing to act as a better muffler, but it is probably good enough to simply make several 180 degree turns. This will create backpressure, so make sure you are getting enough air out of the case.

A project like this is a major undertaking if it is to be done correctly, but it can be done. You can always invest in a KVM switch and amplifier (Belkin makes these) that will allow you to place the CPU a good distance (I think up to 50 feet) away from the keyboard, mouse and monitor and still get good signal. The only trouble is that 1, you must still have adequate ventilation no matter where you put it and 2, you may be out of reach if you are using a computer soundcard or satellite.

To replace your fans or look for quiet alternatives check out....
http://www.directron.com/silence.html

I've purchased fans from them with great success.

For $15.99 you can replace a case fan with a Papst ultra quiet 15db 80 mm case fan. No point in spending $1000 on an ISO box to reduce a 45db stock fan by 20 db if you can get a sub 20db fan for $16 :) In fact they may have lower flow, so get two.

click here ---> http://www.recording.org/e-mag/
scroll down to the bottom of the page and click on "MORE HEADLINES" scroll down that page and click on the headline, "Silence Case"
These cases run around $600 and work very well. I have had my computer in one now for several months and it is dead quiet and cools very well.. Kurt

Thanx everyone for all the informations !. The isoRaxx and the Silence case do cost less than a isoMac, but they are still too expensive for me, for now i can only aford is a DIY isoMac, as Thusmann and Roby did. i saw a design with 2 fans on the top of the back and 4 holes at the bottom with filters, are the fans are used to suck the hot air out from the box and the holes are for fresh air intake or the opposite ?
Anyway to build a wooden box is not a very big problems for me, but my main problem is on the electrical parts, like how to supply power to the fans , on off switch installation ect. does anyone can help me out ? a drawing or whatever ?
Thanx
ray

Whenever possible having the fans for exhaust only is a great help. If you have the box sealed tightly except for the passive air intake (with filters) then you can direct the flow of air around the heat sensitive components. If you use an intake fan, and unless the capacity of the intake fan is greater than the exhaust fan you can wind up with problems. Even with the intake flow greater than exhaust it will cause pressure problems, but that can actually help force air in tight spots.

Bottom line, seal the case up tighly, try to direct the flow from intake around the components, use adequate and quiet exhaust fans with a noise attenuating flow director, and use proper filters on intake so as not to reduce flow. Keep in mind anywhere air escapes or enters, noise will escape. Place intake at the bottom front (cool air is heavier than hot) and exhaust at upper rear (just like in the computer case itself). If you can elevate it off the floor (like with casters) it will help from clogging up the filters as quickly.

As for the fans your local electronics store may be of help. Barring that, http://www.alliedelec.com/ has a nice website with lot's of fans. I'm not sure the best, but I would probably go with larger AC powered fans. Then again, that depends on your case size. You need to calculate the volume of air in the case and compare it to the flow of the fans you are considering. By adding DC fans to your current case power supply remember that you will be taking power away from other devices like disk drives. I'm unaware as to the rating of the Mac's power, but if you've already added a couple additional drives and then add some high flow fans you may be out of luck. Check into this. Factory case fans themselves don't draw much power.

Sorry I don't have any drawing links, but if you go with DC fans, the following may be of help:

http://www.7volts.com/cooling.htm
http://www.hardcorecooling.us/

You can find fan controllers / speed switches for sale, or if you are intersted in making your own speed control switch you can always find links on the web to build them.

Thanx a lot Roby !
i will study a bit first before building this box.
hk