This post is nearly a year old but I would like to put my 2 cents in.
I use big molds so I have never had a chance to use a pressure pot.
I have worked things out were do not have to.
To start up will cost you about $100.
I use Smooth on products. You can buy quart sizes to gallon sized.
I have bought 5 gallon buckets of the RTV ( room temperature vulcanizing ) rubber.
This is your best put for a starter kit. I have used micro mart resin and it is top shelf.
Complete Resin Casting Starter Set
Tips on making molds and casting.
1. I use Legos for my mold boxes and 1/4 plywood to cap the rubber pours off. This helps when using rubber bands so as not to warp the moulds .
2. Use clay or masking tape to hold object to be cast firm .
3. Place lego blocks around piece to make pour box. Make sure you have about 1" space around object.
4. I use OOMOO RTV from Smooth on. It is simple 1 to 1 mix and is forgiving .Fallow direction on containers.
5. When pouring I use those metal handel throw away brushes and paint the object with the RTV. This insure that you do not get air bubbles on the face of the object..
6. the allowed time turn part over take off tape or clay and make sure the part is secure in the mould. Paint with mold release stack more legos then pout the other part. This is the mold release I use and so far it works the best.
Rubber-to-Rubber Mold Release, 2 fl. oz.
It comes with your Micro mark starter kit.
The resin that come with the kit is the slow set. It says that it sets in 30 mins. To be safe give it an hour.
7. When you make your mould try to lay out the parts like you want to pour the. Making sure that the resin will flow to the separate parts.
I FORGOT WHEN YOU MAKE THE FIRST HALF OF THE MOULD I LIKE TO CARCE DIVIT IN THE 1" SURROUND ABOUT EVERY HALF INCH OR SO AROUND. THIS WILL GIVE YOU ALIGHN MENT PINS IN YOUR SECOND HALF OF THE MOULD.
I cut slots in both halves so I get pouring vents .
8. When pouring resin it is important to NOT OVER MIX . This will cause you resin to get hot which will make your resin froth up.
I usually use little clear plastic cups ( Dixie ) . They have ridges on the side making it easier to measure. I mix about 10 seconds and then start pouring.
HERE IS THE TRICKY PART.
Mix the resin then use you throw away brush to paint inside the mold ( part details ) then rubber band the halves together and pour in the resin till it overflows.
Work as fast as you can.
The biggest mold I have made was the Tiger mold it is about 6 inches thick16 inches wide and about 20 inches tall.
That is a lot of rubber !!
I hope this helps. But the best way to learn is trail and error. But it is best to spend a few hours with someone to see how things work.