New cnc machine - Mostly for aluminium

Good day guys

I am in the process of getting materials together to build my machine. This will be my second machine i've build.

It will have a working envelope of 1.6m x 1.5m x 450mm ...I got some of my parts (gantry assembly -- weights +\- 200kg as in pictures atm) of an industrial machine as some other parts as well.

Will be using nema34 throughout (1000 oz), ball screws on all axis's.
I am currently trying to make up my mind between Smoothstepper Ethernet ( $180 + i need to buy a bob PMDX-126 ($174) for it and 3 stepper drivers($78 each)), or the Dynomotion k-flop ($249) + kstep 4 axis bob/driver ($200)

I just cant makeup my mind on how to build my table to make it as rigid as possible. Would love some feedback regarding this. i will upload some pictures of the table
and my gantry as it is currently.

- - - Updated - - -

Machine design so far.
Attachment 319016

Table Design
76mm x 76mm x 4mm square tubing + 10 mm mild steel top. Tubing will also be filled with a silica sand, like those that is found in swimming pool filters.
Table weight as designed in pictures is around 380 kg without sand. The top 10 mm steel top will be surfaced milled where the gantry supports, rails, ball screw mounting etc will be located

Attachment 319018
Attachment 319020
Attachment 319070

Gantry
z-axis 20mm ball screw // y axis 30 mm ballscrew
Will be cutting my connection plate for y & z out of 20 mm vrn 400 steel, also my z-axis plate for rails out of 16 mm vrn 400 steel. Putting order in for plates this week. WIll bring my totlal weight for my gantry assembly without steppers and spindle to around 250kg
Attachment 319022Attachment 319024

Forgot to add : This will be a slow build. Table and cnc back / connection plates will be done shortly....then project will be on hold till more cash flow becomes available.