help in making a 2 story enclosure

[panthergecko]

i want to use the wasted top part of a 20 gallon long.
i want to build a background with great stuff and add some sand or grout for texture.
but on the side want a platform to use the most of the 20 gallon long. including the top part has anyone tried this?
i have 2 leos in 10 gallons so far but want them in more space. also i how long for great stuff to cure? before add some sand or grout?
which kind of great stuff should i use?

plus if you have tried this can i see some pictures?
want to draw plans by sunday.
and should i buy other supplies

 

[Thorgecko707]

i used to make a bookshelf looking system but make the levels smaller as you go up. makes tons of room in a small cage. remember they feel more comfortable in tight spaces so make it two inches high for each level.