To answer to your question yes you can print directly onto the alu build plate but I will not recommend you to do so for the simple reason that if your print stick too well to the platform you’ll end up pulling on the whole printer and might bend rod.
For the glass you can buy one from a local glass reseller it need to be toughened glass and the best will be Borosilicate (this glass is specifically treated to support being heated and cooled think of things like pyrex glass or chemistry glass ) but you can also use most mirror as they are often toughened. In the extreme or desperate situation you can even use the fridge glass that make the shelves, micro wave plate or even oven glass door ofcourse you’ll need to cut those to size most of the time (cutting any of this glass is not different from cutting normal glass)
IKEA use to sell a set of 4 wall mirrors 200mmx200mm but can found them listed anymore they look like this ebay listing
http://www.ebay.com.au/itm/200-200mm-Mirrored-Glass-Print-Bed-Similar-to-Borosilicate-Boro-Reprap-Bed-/261812387240?hash=item3cf53bfda8
The tape or “Platform tape sheet” is often Polyimide (also misspelled polyamide or called Kapton) tape and can be bought in a roll for fraction of the price they will charge in general. Have a look on youtube there is lot of video how to apply it to the glass easily ps: don’t go for dry method but the wet method is the way
http://www.ebay.com.au/itm/5-10-20-30-50-200mm-100ft-Kapton-Tape-High-Temperature-Heat-Resistant-Polyimide-/350801111711?var=&hash=item51ad602a9f
For a bit more info keep reading:
Now in term of covering most people will refer to them as the flavor they prefer for ice cream. IMHO the uhu stick glue, air spray and abs slurry are DIY solution but it doesn’t mean that it’s bad or a bad solution and I explain why. The easiest is the glue stick as most will work I have not found a particular that is better, the air spray is just a pain because if you don’t have the right one it just won’t stick finally the abs slurry is plain nasty a goo that you apply to the bed make a right mess and work mostly for abs however some have success printing PLA onto it.
Perso I use blue painter tape on cold bed and Kapton or Polyimide tape on hot bed the cleaner the better. The most important is bed calibration if the offset (distance between nozzle and bed) is right you can print right onto the glass without anything else assuming you got the right temp.
For cold bed and blue painter tape (I use 3M 2090 be careful as other number don’t have the same texture and won’t work as well unless you know how to print on them ) I recommend to print the first 4 layer at slower speed and the first layer should be really slow and never use Acetone to clean the tape as your next print will stick extremely well to the point you have to tear the print with the tape. With the correct calibration and slow printing of first layers I usually can use the same tape for 2 weeks or more
For hot bed on Kapton tape this will work for almost all material (except flexible filament that will stick incredibly well to the point of not being able to remove the print) and the 2 most important things to understand is
1) cleanliness: Grease from your finger or any other crap might be enough for the extruded plastic to loose it’s grip and start to warp, paper kitchen towel with acetone work well for me.
2) material glass transition: Each material as a value for it’s glass transition for example PLA as a glass transition at 60*C this mean that if you set your bed between 50 and 70 it should work under it might not be hot enough to be near the glass transition and will allow the plastic to shrink back to quickly and warp to hot and you’ll get the bottom of your print deform because the high temp the effect is also called elephant feet because
As above a well calibrated printer will make the part stick well onto Kapton but not to the point it can’t be removed and if your gentle when removing your print the tape can last for up to 2 month easy
a few good pix on this page about pointer of what might go wrong
reprap.org/wiki/Print_Troubleshooting_Pictorial_Guide
I hope this help Bill and happy printing
